{"id":136,"date":"2024-09-11T11:45:00","date_gmt":"2024-09-11T02:45:00","guid":{"rendered":"https:\/\/dexall.co.jp\/articles\/?p=136"},"modified":"2025-03-24T08:55:01","modified_gmt":"2025-03-23T23:55:01","slug":"%e5%88%9d%e5%bf%83%e8%80%85%e3%81%8b%e3%82%89%e3%82%a8%e3%82%ad%e3%82%b9%e3%83%91%e3%83%bc%e3%83%88%e3%81%be%e3%81%a7%e5%ae%8c%e5%85%a8%e7%90%86%e8%a7%a3%ef%bc%81ruby%e3%81%aegroup_by%e3%81%a75","status":"publish","type":"post","link":"https:\/\/dexall.co.jp\/articles\/?p=136","title":{"rendered":"\u521d\u5fc3\u8005\u304b\u3089\u30a8\u30ad\u30b9\u30d1\u30fc\u30c8\u307e\u3067\u5b8c\u5168\u7406\u89e3\uff01Ruby\u306egroup_by\u30675\u500d\u901f\u304f\u306a\u308b\u30c7\u30fc\u30bf\u51e6\u7406\u30c6\u30af\u30cb\u30c3\u30af"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Ruby\u306e<code>group_by<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u30c7\u30fc\u30bf\u51e6\u7406\u306e\u5f37\u529b\u306a\u5473\u65b9\u3067\u3059\u3002<br>\u914d\u5217\u3084\u30cf\u30c3\u30b7\u30e5\u3092\u81ea\u5728\u306b\u64cd\u308a\u3001\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u3092\u7c21\u5358\u306b\u6574\u7406\u3067\u304d\u308b\u3001\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u306e\u4f7f\u3044\u65b9\u3092\u30de\u30b9\u30bf\u30fc\u3059\u308c\u3070\u3001\u3042\u306a\u305f\u306eRuby\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u30b9\u30ad\u30eb\u306f\u4e00\u6c17\u306b\u5411\u4e0a\u3059\u308b\u3067\u3057\u3087\u3046\u3002<br>\u521d\u5fc3\u8005\u304b\u3089\u4e0a\u7d1a\u8005\u307e\u3067\u3001\u5168\u3066\u306eRuby\u958b\u767a\u8005\u306b\u5f79\u7acb\u3064<code>group_by<\/code>\u306e\u9b45\u529b\u3068\u53ef\u80fd\u6027\u3092\u3001\u3053\u306e\u8a18\u4e8b\u3067\u5fb9\u5e95\u7684\u306b\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:var(--wp--preset--color--sango-main);color:#FFF\" class=\"sgb-box-simple__title\">\u3053\u306e\u8a18\u4e8b\u3092\u901a\u3057\u3066\u7406\u89e3\u3067\u304d\u308b7\u3064\u306e\u3053\u3068<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ul class=\"wp-block-list\">\n<li><code>group_by<\/code>\u30e1\u30bd\u30c3\u30c9\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3068\u52d5\u4f5c\u539f\u7406<\/li>\n\n\n\n<li>\u521d\u5fc3\u8005\u3067\u3082\u7406\u89e3\u3067\u304d\u308b\u7c21\u5358\u306a<code>group_by<\/code>\u306e\u5b9f\u8df5\u4f8b<\/li>\n\n\n\n<li>\u4e2d\u7d1a\u8005\u5411\u3051\u306e\u52b9\u7387\u7684\u306a\u30c7\u30fc\u30bf\u64cd\u4f5c\u30c6\u30af\u30cb\u30c3\u30af<\/li>\n\n\n\n<li>\u5927\u898f\u6a21\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3067\u306e<code>group_by<\/code>\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u65b9\u6cd5<\/li>\n\n\n\n<li>\u5b9f\u969b\u306e\u30d3\u30b8\u30cd\u30b9\u30b7\u30fc\u30f3\u306b\u304a\u3051\u308b<code>group_by<\/code>\u306e\u6d3b\u7528\u4f8b<\/li>\n\n\n\n<li><code>group_by<\/code>\u4f7f\u7528\u6642\u306b\u3088\u304f\u3042\u308b\u843d\u3068\u3057\u7a74\u3068\u305d\u306e\u56de\u907f\u7b56<\/li>\n\n\n\n<li><code>group_by<\/code>\u3092\u8db3\u304c\u304b\u308a\u3068\u3057\u305f\u9ad8\u5ea6\u306aRuby\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u6280\u6cd5<\/li>\n<\/ul>\n<\/div><\/div>\n\n\n\n<div class=\"toc\"><br \/>\n<b>Warning<\/b>:  Undefined array key \"is_admin\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>116<\/b><br \/>\n<br \/>\n<b>Warning<\/b>:  Undefined array key \"is_category_top\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>121<\/b><br \/>\n<br \/>\n<b>Warning<\/b>:  Undefined array key \"is_top\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>128<\/b><br \/>\n    <div id=\"toc_container\" class=\"sgb-toc--bullets js-smooth-scroll\" data-dialog-title=\"\u76ee\u6b21\">\n      <p class=\"toc_title\">\u76ee\u6b21 <\/p>\n      <ul class=\"toc_list\">  <li class=\"first\">    <a href=\"#i-0\">1. group_by\u3068\u306f\uff1f\u57fa\u672c\u304b\u3089\u5fdc\u7528\u307e\u3067\u5fb9\u5e95\u89e3\u8aac<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-1\">group_by\u306e\u57fa\u672c\u6982\u5ff5<\/a>      <\/li>      <li>        <a href=\"#i-2\">group_by\u306e\u4e00\u822c\u7684\u306a\u4f7f\u7528\u4f8b<\/a>      <\/li>      <li>        <a href=\"#i-3\">group_by\u306e\u30b7\u30f3\u30bf\u30c3\u30af\u30b9<\/a>      <\/li>      <li>        <a href=\"#i-4\">group_by\u306e\u5fdc\u7528\u4f8b<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-5\">group_by\u306e\u5229\u70b9\u3068\u6ce8\u610f\u70b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-6\">2. \u521d\u5fc3\u8005\u3067\u3082\u7c21\u5358\uff01group_by\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-7\">group_by\u306e\u57fa\u672c\u69cb\u6587<\/a>      <\/li>      <li>        <a href=\"#i-8\">\u6570\u5024\u306e\u5076\u6570\u30fb\u5947\u6570\u5206\u985e\u3067\u7406\u89e3\u3059\u308bgroup_by<\/a>      <\/li>      <li>        <a href=\"#i-9\">\u6587\u5b57\u5217\u306e\u982d\u6587\u5b57\u3067\u30b0\u30eb\u30fc\u30d7\u5316\uff1a\u5b9f\u8df5\u7684\u306a\u4f8b<\/a>      <\/li>      <li>        <a href=\"#i-10\">\u521d\u5fc3\u8005\u304c\u9665\u308a\u3084\u3059\u3044\u9593\u9055\u3044\u3068\u305d\u306e\u56de\u907f\u65b9\u6cd5<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-14\">\u7df4\u7fd2\u554f\u984c<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-19\">3. \u4e2d\u7d1a\u8005\u5fc5\u898b\uff01group_by\u3092\u4f7f\u3063\u305f\u52b9\u7387\u7684\u306a\u30c7\u30fc\u30bf\u64cd\u4f5c<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-20\">\u30cd\u30b9\u30c8\u3057\u305f\u914d\u5217\u3084\u30cf\u30c3\u30b7\u30e5\u306b\u5bfe\u3059\u308bgroup_by\u306e\u9069\u7528\u65b9\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-21\">\u8907\u6570\u306e\u6761\u4ef6\u3092\u7d44\u307f\u5408\u308f\u305b\u305fgroup_by\uff1a\u591a\u6b21\u5143\u30b0\u30eb\u30fc\u30d7\u5316\u306e\u30c6\u30af\u30cb\u30c3\u30af<\/a>      <\/li>      <li>        <a href=\"#i-22\">group_by\u3068\u4ed6\u306eEnumerable\u30e1\u30bd\u30c3\u30c9\u3092\u7d44\u307f\u5408\u308f\u305b\u305f\u52b9\u7387\u7684\u306a\u30c7\u30fc\u30bf\u64cd\u4f5c<\/a>      <\/li>      <li>        <a href=\"#i-25\">\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u306e\u4f7f\u7528\u30b7\u30ca\u30ea\u30aa\uff1aE\u30b3\u30de\u30fc\u30b9\u30b5\u30a4\u30c8\u3067\u306e\u5546\u54c1\u5206\u6790<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-28\">\u307e\u3068\u3081<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-29\">4. \u4e0a\u7d1a\u8005\u5411\u3051\uff1agroup_by\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u3068\u9ad8\u5ea6\u306a\u4f7f\u7528\u4f8b<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-30\">group_by\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u95a2\u3059\u308b\u8003\u616e\u4e8b\u9805<\/a>      <\/li>      <li>        <a href=\"#i-31\">\u5927\u898f\u6a21\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3067\u306egroup_by\u306e\u4f7f\u7528\u65b9\u6cd5\u3068\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af<\/a>      <\/li>      <li>        <a href=\"#i-34\">\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3068\u5b9f\u884c\u901f\u5ea6\u306e\u6539\u5584\u65b9\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-37\">group_by\u3068\u4ed6\u306eEnumerable\u30e1\u30bd\u30c3\u30c9\u306e\u7d44\u307f\u5408\u308f\u305b\u306b\u3088\u308b\u9ad8\u5ea6\u306a\u30c7\u30fc\u30bf\u5206\u6790<\/a>      <\/li>      <li>        <a href=\"#i-40\">\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306b\u304a\u3051\u308b\u9ad8\u5ea6\u306agroup_by\u306e\u4f7f\u7528\u4f8b<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-41\">\u307e\u3068\u3081<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-42\">5. \u5b9f\u8df5\u7684\u306a\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\uff1agroup_by\u3067\u89e3\u6c7a\u3059\u308b\u73fe\u5b9f\u4e16\u754c\u306e\u554f\u984c<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-43\">5.1 \u58f2\u4e0a\u30c7\u30fc\u30bf\u306e\u96c6\u8a08\uff1a\u65e5\u4ed8\u5225\u3001\u88fd\u54c1\u5225\u3001\u9867\u5ba2\u5225\u306e\u5206\u6790\u3092\u4e00\u767a\u3067<\/a>      <\/li>      <li>        <a href=\"#i-46\">5.2 \u30ed\u30b0\u30d5\u30a1\u30a4\u30eb\u306e\u89e3\u6790\uff1a\u30a8\u30e9\u30fc\u30bf\u30a4\u30d7\u5225\u306e\u51fa\u73fe\u983b\u5ea6\u3092group_by\u3067\u77ac\u6642\u306b\u628a\u63e1<\/a>      <\/li>      <li>        <a href=\"#i-49\">5.3 \u305d\u306e\u4ed6\u306e\u5b9f\u8df5\u7684\u306a\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-53\">\u307e\u3068\u3081<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-54\">6. group_by\u30de\u30b9\u30bf\u30fc\u3078\u306e\u9053\uff1a\u3088\u304f\u3042\u308b\u843d\u3068\u3057\u7a74\u3068\u89e3\u6c7a\u7b56<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-55\">6.1 nil\u5024\u3084\u6b20\u640d\u30c7\u30fc\u30bf\u306e\u6271\u3044\uff1agroup_by\u3067\u306e\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u5bfe\u7b56<\/a>      <\/li>      <li>        <a href=\"#i-58\">6.2 \u30d6\u30ed\u30c3\u30af\u30d1\u30e9\u30e1\u30fc\u30bf\u306e\u7406\u89e3\u4e0d\u8db3\u306b\u3088\u308b\u610f\u56f3\u3057\u306a\u3044\u7d50\u679c\u306e\u56de\u907f\u65b9\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-61\">6.3 \u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u554f\u984c\u3068\u6700\u9069\u5316\u65b9\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-63\">6.4 \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u95a2\u3059\u308b\u8003\u616e\u4e8b\u9805\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-67\">6.5 group_by\u4f7f\u7528\u6642\u306e\u30c7\u30d0\u30c3\u30b0\u306e\u30b3\u30c4<\/a>      <\/li>    <\/ul>  <\/li>  <li class=\"last\">    <a href=\"#i-72\">7. \u6b21\u306e\u30b9\u30c6\u30c3\u30d7\uff1agroup_by\u3092\u8d85\u3048\u305f\u9ad8\u5ea6\u306a\u30c7\u30fc\u30bf\u51e6\u7406\u6280\u6cd5<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-73\">7.1 group_by\u304b\u3089\u59cb\u3081\u308b\u95a2\u6570\u578b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u5165\u9580<\/a>      <\/li>      <li>        <a href=\"#i-74\">7.2 \u30c7\u30fc\u30bf\u30b5\u30a4\u30a8\u30f3\u30b9\u3068Ruby\uff1agroup_by\u3092\u6d3b\u7528\u3057\u305f\u7d71\u8a08\u51e6\u7406\u306e\u57fa\u790e<\/a>      <\/li>      <li>        <a href=\"#i-78\">7.3 \u8907\u96d1\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u306b\u5bfe\u3059\u308bgroup_by\u306e\u5fdc\u7528<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-79\">7.4 \u3055\u3089\u306a\u308b\u9ad8\u307f\u3078\uff1a\u4eca\u5f8c\u306e\u5b66\u7fd2\u65b9\u5411\u6027<\/a>      <\/li>    <\/ul>  <\/li><\/ul>\n      <a href=\"#\" class=\"sgb-toc-button js-toc-button\" rel=\"nofollow\" data-open-dialog=\"true\"><i class=\"fa fa-list\"><\/i><span class=\"sgb-toc-button__text\">\u76ee\u6b21\u3078<\/span><\/a>\n    <\/div><\/div><h2 class=\"wp-block-sgb-headings sgb-heading\" id=\"i-0\"><span class=\"sgb-heading__inner sgb-heading--type1 with-icon\" style=\"background-color:transparent;border-color:transparent;font-size:1.2em\"><i class=\"fa fa-check\" style=\"color:var(--wp--preset--color--sango-main)\"><\/i><span class=\"sgb-heading__text\" style=\"color:#333\">1. group_by\u3068\u306f\uff1f\u57fa\u672c\u304b\u3089\u5fdc\u7528\u307e\u3067\u5fb9\u5e95\u89e3\u8aac<\/span><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Ruby\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306b\u304a\u3044\u3066\u3001\u30c7\u30fc\u30bf\u51e6\u7406\u306f\u975e\u5e38\u306b\u91cd\u8981\u306a\u8981\u7d20\u3067\u3059\u3002<br>\u305d\u306e\u4e2d\u3067\u3082<code>group_by<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u64cd\u4f5c\u3092\u7c21\u5358\u306b\u884c\u3048\u308b\u5f37\u529b\u306a\u30c4\u30fc\u30eb\u3067\u3059\u3002<br>\u672c\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>group_by<\/code>\u306e\u57fa\u672c\u6982\u5ff5\u304b\u3089\u5fdc\u7528\u307e\u3067\u3001\u5fb9\u5e95\u7684\u306b\u89e3\u8aac\u3057\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-1\">group_by\u306e\u57fa\u672c\u6982\u5ff5<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306f\u3001Ruby\u306e<code>Enumerable<\/code>\u30e2\u30b8\u30e5\u30fc\u30eb\u306b\u542b\u307e\u308c\u308b\u30e1\u30bd\u30c3\u30c9\u3067\u3001\u914d\u5217\u3084\u30cf\u30c3\u30b7\u30e5\u306a\u3069\u306e\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3092\u7279\u5b9a\u306e\u6761\u4ef6\u3067\u30b0\u30eb\u30fc\u30d7\u5316\u3059\u308b\u6a5f\u80fd\u3092\u63d0\u4f9b\u3057\u307e\u3059\u3002<br>\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u5927\u91cf\u306e\u30c7\u30fc\u30bf\u3092\u77ac\u6642\u306b\u6574\u7406\u3057\u3001\u5206\u6790\u3057\u3084\u3059\u3044\u5f62\u306b\u5909\u63db\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-2\">group_by\u306e\u4e00\u822c\u7684\u306a\u4f7f\u7528\u4f8b<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u914d\u5217\u306e\u8981\u7d20\u3092\u7279\u5b9a\u306e\u5c5e\u6027\u3067\u30b0\u30eb\u30fc\u30d7\u5316<\/li>\n\n\n\n<li>\u30cf\u30c3\u30b7\u30e5\u306e\u8981\u7d20\u3092\u5024\u306e\u7279\u6027\u3067\u30b0\u30eb\u30fc\u30d7\u5316<\/li>\n\n\n\n<li>\u6587\u5b57\u5217\u306e\u914d\u5217\u3092\u982d\u6587\u5b57\u3067\u30b0\u30eb\u30fc\u30d7\u5316<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u308c\u3089\u306e\u64cd\u4f5c\u306f\u3001\u30c7\u30fc\u30bf\u5206\u6790\u3084\u30ec\u30dd\u30fc\u30c8\u4f5c\u6210\u306a\u3069\u3001\u69d8\u3005\u306a\u5834\u9762\u3067\u6d3b\u7528\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-3\">group_by\u306e\u30b7\u30f3\u30bf\u30c3\u30af\u30b9<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306e\u57fa\u672c\u7684\u306a\u30b7\u30f3\u30bf\u30c3\u30af\u30b9\u306f\u4ee5\u4e0b\u306e\u901a\u308a\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">collection.group_by { |item| ... }<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u30d6\u30ed\u30c3\u30af\u5185\u3067\u6307\u5b9a\u3057\u305f\u6761\u4ef6\u306b\u57fa\u3065\u3044\u3066\u3001\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306e\u8981\u7d20\u304c\u30b0\u30eb\u30fc\u30d7\u5316\u3055\u308c\u307e\u3059\u3002<br>\u623b\u308a\u5024\u306f\u3001\u30b0\u30eb\u30fc\u30d7\u5316\u3055\u308c\u305f\u7d50\u679c\u3092\u30cf\u30c3\u30b7\u30e5\u3068\u3057\u3066\u8fd4\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-4\">group_by\u306e\u5fdc\u7528\u4f8b<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u4ee5\u4e0b\u306b\u3001<code>group_by<\/code>\u306e\u5b9f\u8df5\u7684\u306a\u4f7f\u7528\u4f8b\u3092\u793a\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u6570\u5024\u306e\u914d\u5217\u3092\u5076\u6570\u30fb\u5947\u6570\u3067\u30b0\u30eb\u30fc\u30d7\u5316\nnumbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\ngrouped_numbers = numbers.group_by { |n| n.even? ? 'even' : 'odd' }\n# \u7d50\u679c: {'odd' =&gt; [1, 3, 5, 7, 9], 'even' =&gt; [2, 4, 6, 8, 10]}\n\n# \u6587\u5b57\u5217\u306e\u914d\u5217\u3092\u9577\u3055\u3067\u30b0\u30eb\u30fc\u30d7\u5316\nwords = ['cat', 'dog', 'fish', 'bird', 'elephant']\ngrouped_words = words.group_by { |word| word.length }\n# \u7d50\u679c: {3 =&gt; ['cat', 'dog'], 4 =&gt; ['fish', 'bird'], 8 =&gt; ['elephant']}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-5\">group_by\u306e\u5229\u70b9\u3068\u6ce8\u610f\u70b9<\/h3>\n\n\n\n<div class=\"wp-block-sgb-message\"><div class=\"memo sng-shadow-0\" style=\"border-radius:0px;background-color:#b4e0fa;color:#009EF3\"><div class=\"memo_ttl dfont\"><span class=\"sng-box-msg__icon\" style=\"background:#009EF3\"><i class=\"far fa-thumbs-up\"><\/i><\/span><div class=\"sng-box-msg__title\">\u5229\u70b9<\/div><\/div><div class=\"sng-box-msg__contents\">\n<ul class=\"wp-block-list\">\n<li>\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u304c\u5411\u4e0a\u3057\u307e\u3059<\/li>\n\n\n\n<li>\u30c7\u30fc\u30bf\u306e\u6574\u7406\u3068\u5206\u6790\u304c\u5bb9\u6613\u306b\u306a\u308a\u307e\u3059<\/li>\n\n\n\n<li>\u8907\u96d1\u306a\u30eb\u30fc\u30d7\u51e6\u7406\u3092\u7c21\u7565\u5316\u3067\u304d\u307e\u3059<\/li>\n<\/ul>\n<\/div><\/div><\/div>\n\n\n\n<div class=\"wp-block-sgb-message\"><div class=\"memo sng-shadow-0\" style=\"border-radius:0px;background-color:#ffebeb;color:#f88080\"><div class=\"memo_ttl dfont\"><span class=\"sng-box-msg__icon\" style=\"background:#f88080\"><i class=\"fas fa-exclamation\"><\/i><\/span><div class=\"sng-box-msg__title\">\u6ce8\u610f\u70b9<\/div><\/div><div class=\"sng-box-msg__contents\">\n<ul class=\"wp-block-list\">\n<li>\u5927\u898f\u6a21\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3067\u306f\u3001\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306b\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059<\/li>\n\n\n\n<li>\u30d6\u30ed\u30c3\u30af\u306e\u623b\u308a\u5024\u306e\u4e00\u610f\u6027\u3092\u78ba\u4fdd\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059<\/li>\n\n\n\n<li>nil\u5024\u306e\u6271\u3044\u306b\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059<\/li>\n<\/ul>\n<\/div><\/div><\/div>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306f\u975e\u5e38\u306b\u67d4\u8edf\u3067\u5f37\u529b\u306a\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u304c\u3001\u9069\u5207\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002<br>\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3088\u308a\u5177\u4f53\u7684\u306a\u4f7f\u7528\u65b9\u6cd5\u3068\u5b9f\u8df5\u7684\u306a\u4f8b\u3092\u7d39\u4ecb\u3057\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-sgb-headings sgb-heading\" id=\"i-6\"><span class=\"sgb-heading__inner sgb-heading--type1 with-icon\" style=\"background-color:transparent;border-color:transparent;font-size:1.2em\"><i class=\"fa fa-check\" style=\"color:var(--wp--preset--color--sango-main)\"><\/i><span class=\"sgb-heading__text\" style=\"color:#333\">2. \u521d\u5fc3\u8005\u3067\u3082\u7c21\u5358\uff01group_by\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9<\/span><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Ruby\u306e<code>group_by<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u4e00\u898b\u8907\u96d1\u306b\u898b\u3048\u308b\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u304c\u3001\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u306f\u975e\u5e38\u306b\u30b7\u30f3\u30d7\u30eb\u3067\u3059\u3002<br>\u3053\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u521d\u5fc3\u8005\u306e\u65b9\u3067\u3082\u7c21\u5358\u306b\u7406\u89e3\u3067\u304d\u308b\u3088\u3046\u3001\u5177\u4f53\u7684\u306a\u4f8b\u3092\u4ea4\u3048\u306a\u304c\u3089\u89e3\u8aac\u3057\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-7\">group_by\u306e\u57fa\u672c\u69cb\u6587<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306e\u57fa\u672c\u7684\u306a\u69cb\u6587\u306f\u4ee5\u4e0b\u306e\u901a\u308a\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">array.group_by { |element| ... }<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u3053\u3067\u3001<code>array<\/code>\u306f\u51e6\u7406\u5bfe\u8c61\u306e\u914d\u5217\u3067\u3001\u30d6\u30ed\u30c3\u30af\u5185\uff08<code>{ }<\/code>\u306e\u4e2d\uff09\u306b\u30b0\u30eb\u30fc\u30d7\u5316\u306e\u6761\u4ef6\u3092\u8a18\u8ff0\u3057\u307e\u3059\u3002<br>\u623b\u308a\u5024\u306f\u3001\u30b0\u30eb\u30fc\u30d7\u5316\u3055\u308c\u305f\u7d50\u679c\u3092\u542b\u3080\u30cf\u30c3\u30b7\u30e5\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-8\">\u6570\u5024\u306e\u5076\u6570\u30fb\u5947\u6570\u5206\u985e\u3067\u7406\u89e3\u3059\u308bgroup_by<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u6700\u3082\u5206\u304b\u308a\u3084\u3059\u3044<code>group_by<\/code>\u306e\u4f8b\u3068\u3057\u3066\u3001\u6570\u5024\u306e\u5076\u6570\u30fb\u5947\u6570\u5206\u985e\u3092\u898b\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">numbers = [1, 2, 3, 4, 5, 6]\nresult = numbers.group_by { |n| n.even? ? 'even' : 'odd' }\nputs result\n# \u51fa\u529b: {\"odd\"=&gt;[1, 3, 5], \"even\"=&gt;[2, 4, 6]}<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u30b3\u30fc\u30c9\u306e\u52d5\u4f5c\u3092\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><code>numbers<\/code>\u914d\u5217\u306e\u5404\u8981\u7d20\u306b\u5bfe\u3057\u3066\u3001\u30d6\u30ed\u30c3\u30af\u5185\u306e\u51e6\u7406\u304c\u5b9f\u884c\u3055\u308c\u307e\u3059\u3002<\/li>\n\n\n\n<li><code>n.even?<\/code>\u306f\u3001\u6570\u304c\u5076\u6570\u306e\u5834\u5408\u306b<code>true<\/code>\u3092\u8fd4\u3057\u307e\u3059\u3002<\/li>\n\n\n\n<li>\u4e09\u9805\u6f14\u7b97\u5b50 <code>? :<\/code>\u3092\u4f7f\u7528\u3057\u3066\u3001\u5076\u6570\u306a\u3089\u2019even\u2019\u3001\u5947\u6570\u306a\u3089\u2019odd\u2019\u3092\u8fd4\u3057\u307e\u3059\u3002<\/li>\n\n\n\n<li>\u623b\u308a\u5024\u306e\u30cf\u30c3\u30b7\u30e5\u3067\u306f\u3001\u2019odd\u2019\u3068\u2019even\u2019\u304c\u30ad\u30fc\u3068\u306a\u308a\u3001\u305d\u308c\u305e\u308c\u306e\u6570\u5024\u304c\u5bfe\u5fdc\u3059\u308b\u914d\u5217\u306b\u683c\u7d0d\u3055\u308c\u307e\u3059\u3002<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-9\">\u6587\u5b57\u5217\u306e\u982d\u6587\u5b57\u3067\u30b0\u30eb\u30fc\u30d7\u5316\uff1a\u5b9f\u8df5\u7684\u306a\u4f8b<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u6b21\u306b\u3001\u6587\u5b57\u5217\u306e\u914d\u5217\u3092\u982d\u6587\u5b57\u3067\u30b0\u30eb\u30fc\u30d7\u5316\u3059\u308b\u4f8b\u3092\u898b\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">words = ['apple', 'banana', 'cherry', 'date']\nresult = words.group_by { |word| word[0] }\nputs result\n# \u51fa\u529b: {\"a\"=&gt;[\"apple\"], \"b\"=&gt;[\"banana\"], \"c\"=&gt;[\"cherry\"], \"d\"=&gt;[\"date\"]}<\/pre>\n\n\n\n<div class=\"wp-block-sgb-message\"><div class=\"memo sng-shadow-0\" style=\"border-radius:0px;background-color:#b4e0fa;color:#009EF3\"><div class=\"memo_ttl dfont\"><span class=\"sng-box-msg__icon\" style=\"background:#009EF3\"><i class=\"far fa-lightbulb\"><\/i><\/span><div class=\"sng-box-msg__title\">\u4e0a\u8a18\u4f8b\u306e\u89e3\u8aac<\/div><\/div><div class=\"sng-box-msg__contents\">\n<ol class=\"wp-block-list\">\n<li>\u5404\u5358\u8a9e\u306e\u6700\u521d\u306e\u6587\u5b57\uff08<code>word[0]<\/code>\uff09\u3092\u30b0\u30eb\u30fc\u30d7\u5316\u306e\u30ad\u30fc\u3068\u3057\u3066\u4f7f\u7528\u3057\u3066\u3044\u307e\u3059\u3002<\/li>\n\n\n\n<li>\u7d50\u679c\u3068\u3057\u3066\u3001\u982d\u6587\u5b57\u3092\u30ad\u30fc\u3068\u3057\u3001\u305d\u306e\u6587\u5b57\u3067\u59cb\u307e\u308b\u5358\u8a9e\u306e\u30ea\u30b9\u30c8\u3092\u5024\u3068\u3059\u308b\u30cf\u30c3\u30b7\u30e5\u304c\u5f97\u3089\u308c\u307e\u3059\u3002<\/li>\n<\/ol>\n<\/div><\/div><\/div>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-10\">\u521d\u5fc3\u8005\u304c\u9665\u308a\u3084\u3059\u3044\u9593\u9055\u3044\u3068\u305d\u306e\u56de\u907f\u65b9\u6cd5<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u3092\u4f7f\u3046\u969b\u306b\u3001\u521d\u5fc3\u8005\u304c\u3088\u304f\u9665\u308b\u9593\u9055\u3044\u3068\u305d\u306e\u56de\u907f\u65b9\u6cd5\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-11\">1. <strong>\u30d6\u30ed\u30c3\u30af\u306e\u623b\u308a\u5024\u3092\u6307\u5b9a\u3057\u5fd8\u308c\u308b<\/strong><\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u9593\u9055\u3044: <code>numbers.group_by { |n| n.even? }<\/code><\/li>\n\n\n\n<li>\u6b63\u3057\u3044\u4f7f\u3044\u65b9: <code>numbers.group_by { |n| n.even? ? true : false }<\/code><\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-12\">2. <strong>\u30b0\u30eb\u30fc\u30d7\u5316\u306e\u30ad\u30fc\u3068\u3057\u3066\u4e0d\u9069\u5207\u306a\u5024\u3092\u4f7f\u7528\u3059\u308b<\/strong><\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u9593\u9055\u3044: <code>words.group_by { |word| word.length &gt; 5 }<\/code><\/li>\n\n\n\n<li>\u6b63\u3057\u3044\u4f7f\u3044\u65b9: <code>words.group_by { |word| word.length &gt; 5 ? 'long' : 'short' }<\/code><\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-13\">3. <strong>\u623b\u308a\u5024\u306e\u30c7\u30fc\u30bf\u69cb\u9020\u3092\u8aa4\u89e3\u3059\u308b<\/strong><\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u8aa4\u89e3: \u30b0\u30eb\u30fc\u30d7\u5316\u306e\u7d50\u679c\u304c\u914d\u5217\u306b\u306a\u308b\u3068\u601d\u3044\u8fbc\u3080<\/li>\n\n\n\n<li>\u6b63\u3057\u3044\u7406\u89e3: \u7d50\u679c\u306f\u30cf\u30c3\u30b7\u30e5\u3067\u3042\u308a\u3001\u30ad\u30fc\u304c\u30b0\u30eb\u30fc\u30d7\u540d\u3001\u5024\u304c\u5bfe\u5fdc\u3059\u308b\u8981\u7d20\u306e\u914d\u5217<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-14\">\u7df4\u7fd2\u554f\u984c<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u7406\u89e3\u5ea6\u3092\u78ba\u8a8d\u3059\u308b\u305f\u3081\u306b\u3001\u4ee5\u4e0b\u306e\u7df4\u7fd2\u554f\u984c\u306b\u6311\u6226\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-15\">1. \u5e74\u9f62\u306e\u30ea\u30b9\u30c8\u3092\u300c\u672a\u6210\u5e74\u300d\u3068\u300c\u6210\u4eba\u300d\u306b\u30b0\u30eb\u30fc\u30d7\u5316\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">ages = [15, 22, 18, 30, 17, 25]\n# \u3053\u3053\u306b\u30b3\u30fc\u30c9\u3092\u66f8\u3044\u3066\u304f\u3060\u3055\u3044<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-16\">2. \u6587\u5b57\u5217\u306e\u30ea\u30b9\u30c8\u3092\u9577\u3055\u3067\u30b0\u30eb\u30fc\u30d7\u5316\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">words = ['cat', 'dog', 'elephant', 'fox', 'giraffe']\n# \u3053\u3053\u306b\u30b3\u30fc\u30c9\u3092\u66f8\u3044\u3066\u304f\u3060\u3055\u3044<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u89e3\u7b54\u4f8b\u306f\u6b21\u306e\u3068\u304a\u308a\u3067\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-17\">3. \u5e74\u9f62\u306e\u30b0\u30eb\u30fc\u30d7\u5316<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">result = ages.group_by { |age| age &lt; 20 ? '\u672a\u6210\u5e74' : '\u6210\u4eba' }\nputs result\n# \u51fa\u529b: {\"\u672a\u6210\u5e74\"=&gt;[15, 18, 17], \"\u6210\u4eba\"=&gt;[22, 30, 25]}<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-18\">4. \u6587\u5b57\u5217\u306e\u9577\u3055\u3067\u306e\u30b0\u30eb\u30fc\u30d7\u5316<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">result = words.group_by { |word| word.length }\nputs result\n# \u51fa\u529b: {3=&gt;[\"cat\", \"dog\", \"fox\"], 8=&gt;[\"elephant\"], 7=&gt;[\"giraffe\"]}<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u308c\u3089\u306e\u4f8b\u3092\u901a\u3058\u3066\u3001<code>group_by<\/code>\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3092\u7406\u89e3\u3067\u304d\u305f\u3067\u3057\u3087\u3046\u304b\uff1f<br>\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3088\u308a\u9ad8\u5ea6\u306a\u4f7f\u7528\u65b9\u6cd5\u306b\u3064\u3044\u3066\u89e3\u8aac\u3057\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-sgb-headings sgb-heading\" id=\"i-19\"><span class=\"sgb-heading__inner sgb-heading--type1 with-icon\" style=\"background-color:transparent;border-color:transparent;font-size:1.2em\"><i class=\"fa fa-check\" style=\"color:var(--wp--preset--color--sango-main)\"><\/i><span class=\"sgb-heading__text\" style=\"color:#333\">3. \u4e2d\u7d1a\u8005\u5fc5\u898b\uff01group_by\u3092\u4f7f\u3063\u305f\u52b9\u7387\u7684\u306a\u30c7\u30fc\u30bf\u64cd\u4f5c<\/span><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u30e1\u30bd\u30c3\u30c9\u306e\u57fa\u672c\u3092\u7406\u89e3\u3057\u305f\u3089\u3001\u6b21\u306f\u3088\u308a\u9ad8\u5ea6\u306a\u4f7f\u3044\u65b9\u3092\u5b66\u3073\u307e\u3057\u3087\u3046\u3002<br>\u3053\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u4e2d\u7d1a\u8005\u5411\u3051\u306b<code>group_by<\/code>\u3092\u4f7f\u3063\u305f\u52b9\u7387\u7684\u306a\u30c7\u30fc\u30bf\u64cd\u4f5c\u30c6\u30af\u30cb\u30c3\u30af\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<br>\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u306e\u6271\u3044\u65b9\u304b\u3089\u3001\u4ed6\u306e\u30e1\u30bd\u30c3\u30c9\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\u307e\u3067\u3001\u5b9f\u8df5\u7684\u306a\u4f8b\u3092\u4ea4\u3048\u3066\u89e3\u8aac\u3057\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-20\">\u30cd\u30b9\u30c8\u3057\u305f\u914d\u5217\u3084\u30cf\u30c3\u30b7\u30e5\u306b\u5bfe\u3059\u308bgroup_by\u306e\u9069\u7528\u65b9\u6cd5<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u306f\u3001\u5358\u7d14\u306a\u914d\u5217\u3060\u3051\u3067\u306a\u304f\u3001\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u3092\u6271\u3046\u3053\u3068\u304c\u591a\u3005\u3042\u308a\u307e\u3059\u3002<br>\u4f8b\u3048\u3070\u3001\u30e6\u30fc\u30b6\u30fc\u60c5\u5831\u3092\u542b\u3080\u30cf\u30c3\u30b7\u30e5\u306e\u914d\u5217\u3092\u90fd\u5e02\u5225\u306b\u30b0\u30eb\u30fc\u30d7\u5316\u3059\u308b\u5834\u5408\u3092\u8003\u3048\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">users = [\n  {name: 'Alice', age: 30, city: 'New York'},\n  {name: 'Bob', age: 25, city: 'Los Angeles'},\n  {name: 'Charlie', age: 35, city: 'New York'}\n]\n\nresult = users.group_by { |user| user[:city] }\nputs result\n# \u51fa\u529b:\n# {\n#   \"New York\"=&gt;[{:name=&gt;\"Alice\", :age=&gt;30, :city=&gt;\"New York\"}, {:name=&gt;\"Charlie\", :age=&gt;35, :city=&gt;\"New York\"}],\n#   \"Los Angeles\"=&gt;[{:name=&gt;\"Bob\", :age=&gt;25, :city=&gt;\"Los Angeles\"}]\n# }<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u4f8b\u3067\u306f\u3001\u5404\u30e6\u30fc\u30b6\u30fc\u306e<code>:city<\/code>\u3092\u30ad\u30fc\u3068\u3057\u3066\u30b0\u30eb\u30fc\u30d7\u5316\u3057\u3066\u3044\u307e\u3059\u3002<br>\u7d50\u679c\u3068\u3057\u3066\u3001\u90fd\u5e02\u540d\u3092\u30ad\u30fc\u3068\u3057\u3001\u305d\u306e\u90fd\u5e02\u306e\u30e6\u30fc\u30b6\u30fc\u60c5\u5831\u3092\u307e\u3068\u3081\u305f\u914d\u5217\u3092\u5024\u3068\u3059\u308b\u30cf\u30c3\u30b7\u30e5\u304c\u5f97\u3089\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-21\">\u8907\u6570\u306e\u6761\u4ef6\u3092\u7d44\u307f\u5408\u308f\u305b\u305fgroup_by\uff1a\u591a\u6b21\u5143\u30b0\u30eb\u30fc\u30d7\u5316\u306e\u30c6\u30af\u30cb\u30c3\u30af<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u3088\u308a\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u5206\u6790\u3067\u306f\u3001\u8907\u6570\u306e\u6761\u4ef6\u3092\u7d44\u307f\u5408\u308f\u305b\u3066\u30b0\u30eb\u30fc\u30d7\u5316\u3059\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002<br>\u4ee5\u4e0b\u306f\u3001\u5546\u54c1\u30c7\u30fc\u30bf\u3092\u5206\u985e\u3059\u308b\u4f8b\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">data = [\n  {product: 'A', category: 'X', sales: 100},\n  {product: 'B', category: 'Y', sales: 200},\n  {product: 'C', category: 'X', sales: 150}\n]\n\nresult = data.group_by { |item| [item[:category], item[:sales] &gt; 150] }\nputs result\n# \u51fa\u529b:\n# {\n#   [\"X\", false]=&gt;[{:product=&gt;\"A\", :category=&gt;\"X\", :sales=&gt;100}, {:product=&gt;\"C\", :category=&gt;\"X\", :sales=&gt;150}],\n#   [\"Y\", true]=&gt;[{:product=&gt;\"B\", :category=&gt;\"Y\", :sales=&gt;200}]\n# }<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u4f8b\u3067\u306f\u3001\u30ab\u30c6\u30b4\u30ea\u30fc\u3068\u58f2\u4e0a\u9ad8\uff08150\u3092\u8d85\u3048\u308b\u304b\u3069\u3046\u304b\uff09\u306e2\u3064\u306e\u6761\u4ef6\u3067\u30b0\u30eb\u30fc\u30d7\u5316\u3057\u3066\u3044\u307e\u3059\u3002<br>\u30ad\u30fc\u304c\u914d\u5217\u306b\u306a\u3063\u3066\u3044\u308b\u305f\u3081\u3001\u591a\u6b21\u5143\u306e\u30b0\u30eb\u30fc\u30d7\u5316\u304c\u5b9f\u73fe\u3067\u304d\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u3055\u3089\u306b\u8907\u96d1\u306a\u591a\u6b21\u5143\u30b0\u30eb\u30fc\u30d7\u5316\u306e\u4f8b\u3092\u898b\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">people = [\n  {name: 'Alice', age: 30, department: 'IT'},\n  {name: 'Bob', age: 25, department: 'HR'},\n  {name: 'Charlie', age: 35, department: 'IT'}\n]\n\nresult = people.group_by { |person| [person[:department], person[:age] \/ 10 * 10] }\nputs result\n# \u51fa\u529b:\n# {\n#   [\"IT\", 30]=&gt;[{:name=&gt;\"Alice\", :age=&gt;30, :department=&gt;\"IT\"}, {:name=&gt;\"Charlie\", :age=&gt;35, :department=&gt;\"IT\"}],\n#   [\"HR\", 20]=&gt;[{:name=&gt;\"Bob\", :age=&gt;25, :department=&gt;\"HR\"}]\n# }<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u4f8b\u3067\u306f\u3001\u90e8\u7f72\u3068\u5e74\u4ee3\uff0810\u6b73\u523b\u307f\uff09\u3067\u591a\u6b21\u5143\u30b0\u30eb\u30fc\u30d7\u5316\u3057\u3066\u3044\u307e\u3059\u3002<br>\u3053\u308c\u306b\u3088\u308a\u3001\u90e8\u7f72\u3054\u3068\u306e\u5e74\u4ee3\u5225\u306e\u5206\u6790\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-22\">group_by\u3068\u4ed6\u306eEnumerable\u30e1\u30bd\u30c3\u30c9\u3092\u7d44\u307f\u5408\u308f\u305b\u305f\u52b9\u7387\u7684\u306a\u30c7\u30fc\u30bf\u64cd\u4f5c<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306e\u771f\u4fa1\u306f\u3001\u4ed6\u306eEnumerable\u30e1\u30bd\u30c3\u30c9\u3068\u7d44\u307f\u5408\u308f\u305b\u305f\u3068\u304d\u306b\u767a\u63ee\u3055\u308c\u307e\u3059\u3002<br>\u4ee5\u4e0b\u306b\u3001\u3044\u304f\u3064\u304b\u306e\u5f37\u529b\u306a\u7d44\u307f\u5408\u308f\u305b\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-23\">group_by \u3068 map \u306e\u7d44\u307f\u5408\u308f\u305b<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u5076\u6570\u3068\u5947\u6570\u306b\u5206\u985e\u3057\u3001\u305d\u308c\u305e\u308c\u306e\u5408\u8a08\u3092\u8a08\u7b97\u3059\u308b\u4f8b\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\nresult = numbers.group_by { |n| n.even? ? 'even' : 'odd' }\n                .transform_values { |v| v.sum }\nputs result\n# \u51fa\u529b: {\"odd\"=&gt;25, \"even\"=&gt;30}<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u4f8b\u3067\u306f\u3001<code>transform_values<\/code>\u30e1\u30bd\u30c3\u30c9\uff08<code>map<\/code>\u3068\u540c\u69d8\u306e\u50cd\u304d\uff09\u3092\u4f7f\u3063\u3066\u3001\u30b0\u30eb\u30fc\u30d7\u5316\u3055\u308c\u305f\u5404\u914d\u5217\u306e\u5408\u8a08\u3092\u8a08\u7b97\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-24\">group_by \u3068 reduce \u306e\u7d44\u307f\u5408\u308f\u305b<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u6587\u5b57\u5217\u306e\u914d\u5217\u3092\u982d\u6587\u5b57\u3067\u30b0\u30eb\u30fc\u30d7\u5316\u3057\u3001\u5404\u30b0\u30eb\u30fc\u30d7\u306e\u4e2d\u3067\u6700\u3082\u9577\u3044\u5358\u8a9e\u3092\u9078\u629e\u3059\u308b\u4f8b\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">words = ['apple', 'banana', 'cherry', 'date', 'elderberry', 'fig']\nresult = words.group_by { |w| w[0] }\n              .transform_values { |v| v.reduce { |memo, word| memo.length &gt; word.length ? memo : word } }\nputs result\n# \u51fa\u529b: {\"a\"=&gt;\"apple\", \"b\"=&gt;\"banana\", \"c\"=&gt;\"cherry\", \"d\"=&gt;\"date\", \"e\"=&gt;\"elderberry\", \"f\"=&gt;\"fig\"}<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u4f8b\u3067\u306f\u3001<code>reduce<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u3063\u3066\u5404\u30b0\u30eb\u30fc\u30d7\u5185\u3067\u6700\u9577\u306e\u5358\u8a9e\u3092\u9078\u629e\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-25\">\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u306e\u4f7f\u7528\u30b7\u30ca\u30ea\u30aa\uff1aE\u30b3\u30de\u30fc\u30b9\u30b5\u30a4\u30c8\u3067\u306e\u5546\u54c1\u5206\u6790<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u6700\u5f8c\u306b\u3001\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067<code>group_by<\/code>\u304c\u3069\u306e\u3088\u3046\u306b\u4f7f\u7528\u3055\u308c\u308b\u304b\u3092\u793a\u3059\u4f8b\u3092\u898b\u3066\u307f\u307e\u3057\u3087\u3046\u3002<br>\u4ee5\u4e0b\u306f\u3001E\u30b3\u30de\u30fc\u30b9\u30b5\u30a4\u30c8\u306e\u5546\u54c1\u30c7\u30fc\u30bf\u3092\u5206\u6790\u3059\u308b\u30b7\u30ca\u30ea\u30aa\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">products = [\n  {name: 'Laptop', category: 'Electronics', price: 1000, stock: 50},\n  {name: 'Smartphone', category: 'Electronics', price: 500, stock: 100},\n  {name: 'Desk', category: 'Furniture', price: 200, stock: 30},\n  {name: 'Chair', category: 'Furniture', price: 100, stock: 60}\n]\n\nanalysis = products.group_by { |p| p[:category] }\n                   .transform_values do |items|\n                     {\n                       total_value: items.sum { |item| item[:price] * item[:stock] },\n                       average_price: items.sum { |item| item[:price] } \/ items.length,\n                       item_count: items.length\n                     }\n                   end\n\nputs analysis\n# \u51fa\u529b:\n# {\n#   \"Electronics\"=&gt;{:total_value=&gt;100000, :average_price=&gt;750.0, :item_count=&gt;2},\n#   \"Furniture\"=&gt;{:total_value=&gt;12000, :average_price=&gt;150.0, :item_count=&gt;2}\n# }<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u4f8b\u3067\u306f\u3001\u4ee5\u4e0b\u306e\u64cd\u4f5c\u3092\u884c\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-26\">1. \u5546\u54c1\u3092\u30ab\u30c6\u30b4\u30ea\u30fc\u3067\u30b0\u30eb\u30fc\u30d7\u5316<\/h4>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-27\">2. \u5404\u30ab\u30c6\u30b4\u30ea\u30fc\u306b\u3064\u3044\u3066\u4ee5\u4e0b\u3092\u8a08\u7b97<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u7dcf\u5728\u5eab\u4fa1\u5024\uff08\u4fa1\u683c \u00d7 \u5728\u5eab\u6570\u306e\u5408\u8a08\uff09<\/li>\n\n\n\n<li>\u5e73\u5747\u4fa1\u683c<\/li>\n\n\n\n<li>\u30a2\u30a4\u30c6\u30e0\u6570<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u3088\u3046\u306a\u5206\u6790\u306f\u3001\u5728\u5eab\u7ba1\u7406\u3084\u4fa1\u683c\u6226\u7565\u306e\u7acb\u6848\u306b\u5f79\u7acb\u3061\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-28\">\u307e\u3068\u3081<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>group_by<\/code>\u30e1\u30bd\u30c3\u30c9\u306e\u9ad8\u5ea6\u306a\u4f7f\u7528\u65b9\u6cd5\u3092\u5b66\u3073\u307e\u3057\u305f\u3002<br>\u30cd\u30b9\u30c8\u3057\u305f\u30c7\u30fc\u30bf\u69cb\u9020\u306e\u6271\u3044\u65b9\u3001\u591a\u6b21\u5143\u30b0\u30eb\u30fc\u30d7\u5316\u3001\u4ed6\u306e\u30e1\u30bd\u30c3\u30c9\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\u3001\u305d\u3057\u3066\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u306e\u5fdc\u7528\u4f8b\u3092\u898b\u3066\u304d\u307e\u3057\u305f\u3002<br>\u3053\u308c\u3089\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3092\u4f7f\u3044\u3053\u306a\u3059\u3053\u3068\u3067\u3001\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u64cd\u4f5c\u3092\u52b9\u7387\u7684\u306b\u884c\u3046\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3055\u3089\u306b\u9ad8\u5ea6\u306a\u30c8\u30d4\u30c3\u30af\u3068\u3057\u3066\u3001<code>group_by<\/code>\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u3068\u3001\u3088\u308a\u6d17\u7df4\u3055\u308c\u305f\u4f7f\u7528\u4f8b\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-sgb-headings sgb-heading\" id=\"i-29\"><span class=\"sgb-heading__inner sgb-heading--type1 with-icon\" style=\"background-color:transparent;border-color:transparent;font-size:1.2em\"><i class=\"fa fa-check\" style=\"color:var(--wp--preset--color--sango-main)\"><\/i><span class=\"sgb-heading__text\" style=\"color:#333\">4. \u4e0a\u7d1a\u8005\u5411\u3051\uff1agroup_by\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u3068\u9ad8\u5ea6\u306a\u4f7f\u7528\u4f8b<\/span><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u975e\u5e38\u306b\u5f37\u529b\u3067\u3059\u304c\u3001\u5927\u898f\u6a21\u306a\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3084\u8907\u96d1\u306a\u64cd\u4f5c\u3092\u6271\u3046\u5834\u5408\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u554f\u984c\u306b\u76f4\u9762\u3059\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002<br>\u3053\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>group_by<\/code>\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af\u3068\u3001\u3088\u308a\u9ad8\u5ea6\u306a\u4f7f\u7528\u4f8b\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-30\">group_by\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u95a2\u3059\u308b\u8003\u616e\u4e8b\u9805<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u3092\u52b9\u7387\u7684\u306b\u4f7f\u7528\u3059\u308b\u306b\u306f\u3001\u4ee5\u4e0b\u306e\u70b9\u3092\u8003\u616e\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<div class=\"wp-block-sgb-message\"><div class=\"memo sng-shadow-0\" style=\"border-radius:0px;background-color:#ffebeb;color:#f88080\"><div class=\"memo_ttl dfont\"><span class=\"sng-box-msg__icon\" style=\"background:#f88080\"><i class=\"fas fa-exclamation\"><\/i><\/span><div class=\"sng-box-msg__title\"><code>group_by<\/code>\u5229\u7528\u6642\u306e\u6ce8\u610f\u70b9<\/div><\/div><div class=\"sng-box-msg__contents\">\n<ol class=\"wp-block-list\">\n<li><strong>\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u306e\u30b5\u30a4\u30ba\u3068\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf<\/strong>\uff1a<code>group_by<\/code>\u306f\u5168\u3066\u306e\u8981\u7d20\u3092\u30e1\u30e2\u30ea\u306b\u4fdd\u6301\u3059\u308b\u305f\u3081\u3001\u5927\u898f\u6a21\u306a\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3067\u306f\u591a\u304f\u306e\u30e1\u30e2\u30ea\u3092\u6d88\u8cbb\u3057\u307e\u3059\u3002<\/li>\n\n\n\n<li><strong>\u30d6\u30ed\u30c3\u30af\u5185\u306e\u51e6\u7406\u306e\u8907\u96d1\u3055<\/strong>\uff1a\u30d6\u30ed\u30c3\u30af\u5185\u306e\u51e6\u7406\u304c\u8907\u96d1\u306b\u306a\u308b\u307b\u3069\u3001\u5b9f\u884c\u6642\u9593\u304c\u9577\u304f\u306a\u308a\u307e\u3059\u3002<\/li>\n\n\n\n<li><strong>\u30ad\u30fc\u306e\u9078\u629e<\/strong>\uff1a\u30b0\u30eb\u30fc\u30d7\u5316\u306e\u30ad\u30fc\u306e\u9078\u3073\u65b9\u306b\u3088\u3063\u3066\u3001\u7d50\u679c\u306e\u52b9\u7387\u3068\u6709\u7528\u6027\u304c\u5927\u304d\u304f\u5909\u308f\u308a\u307e\u3059\u3002<\/li>\n<\/ol>\n<\/div><\/div><\/div>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-31\">\u5927\u898f\u6a21\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3067\u306egroup_by\u306e\u4f7f\u7528\u65b9\u6cd5\u3068\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5927\u898f\u6a21\u306a\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3092\u6271\u3046\u5834\u5408\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30c6\u30af\u30cb\u30c3\u30af\u304c\u6709\u52b9\u3067\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-32\">1. \u9045\u5ef6\u8a55\u4fa1\uff08Lazy Enumeration\uff09\u306e\u4f7f\u7528<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\"><code>lazy<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u5fc5\u8981\u306a\u90e8\u5206\u3060\u3051\u3092\u8a55\u4fa1\u3057\u3001\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u6291\u3048\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">require 'enumerator'\n\nresult = data.group_by { |item| item[:category] }\n            .lazy\n            .take(10)\n            .force\n\nputs result<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u4f8b\u3067\u306f\u3001\u6700\u521d\u306e10\u500b\u306e\u30b0\u30eb\u30fc\u30d7\u3060\u3051\u3092\u53d6\u5f97\u3057\u3066\u3044\u307e\u3059\u3002<br><code>force<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u547c\u3073\u51fa\u3059\u307e\u3067\u5b9f\u969b\u306e\u8a55\u4fa1\u306f\u884c\u308f\u308c\u307e\u305b\u3093\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-33\">2. \u30d0\u30c3\u30c1\u51e6\u7406<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u5927\u898f\u6a21\u306a\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3092\u5c0f\u3055\u306a\u30d0\u30c3\u30c1\u306b\u5206\u3051\u3066\u51e6\u7406\u3059\u308b\u3053\u3068\u3067\u3001\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u5236\u5fa1\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">data.each_slice(1000) do |batch|\n  result = batch.group_by { |item| item[:category] }\n  # \u5404\u30d0\u30c3\u30c1\u306e\u51e6\u7406\nend<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u65b9\u6cd5\u306f\u3001\u30c7\u30fc\u30bf\u30b9\u30c8\u30ea\u30fc\u30e0\u3084\u5927\u304d\u306a\u30d5\u30a1\u30a4\u30eb\u3092\u51e6\u7406\u3059\u308b\u969b\u306b\u7279\u306b\u6709\u52b9\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-34\">\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3068\u5b9f\u884c\u901f\u5ea6\u306e\u6539\u5584\u65b9\u6cd5<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-35\">1. \u30b7\u30f3\u30dc\u30eb\u306e\u4f7f\u7528<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u6587\u5b57\u5217\u306e\u4ee3\u308f\u308a\u306b\u30b7\u30f3\u30dc\u30eb\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u524a\u6e1b\u3057\u3001\u51e6\u7406\u901f\u5ea6\u3092\u5411\u4e0a\u3055\u305b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">data.group_by { |item| item[:category].to_sym }<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-36\">2. \u30ad\u30fc\u306e\u4e8b\u524d\u8a08\u7b97<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u30b0\u30eb\u30fc\u30d7\u5316\u306e\u30ad\u30fc\u3092\u4e8b\u524d\u306b\u8a08\u7b97\u3059\u308b\u3053\u3068\u3067\u3001<code>group_by<\/code>\u306e\u51e6\u7406\u3092\u6700\u9069\u5316\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">categories = data.map { |item| item[:category] }.uniq\nresult = categories.each_with_object({}) do |cat, result|\n  result[cat] = data.select { |item| item[:category] == cat }\nend<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u65b9\u6cd5\u306f\u3001\u7279\u306b\u5927\u898f\u6a21\u306a\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3067\u52b9\u679c\u7684\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-37\">group_by\u3068\u4ed6\u306eEnumerable\u30e1\u30bd\u30c3\u30c9\u306e\u7d44\u307f\u5408\u308f\u305b\u306b\u3088\u308b\u9ad8\u5ea6\u306a\u30c7\u30fc\u30bf\u5206\u6790<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u3092\u4ed6\u306e\u30e1\u30bd\u30c3\u30c9\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u6d17\u7df4\u3055\u308c\u305f\u5206\u6790\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-38\">1. group_by\u3068reduce\u306e\u7d44\u307f\u5408\u308f\u305b<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u30ab\u30c6\u30b4\u30ea\u3054\u3068\u306e\u5408\u8a08\u5024\u3092\u8a08\u7b97\u3059\u308b\u4f8b<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">result = data.group_by { |item| item[:category] }\n             .transform_values { |items| items.reduce(0) { |sum, item| sum + item[:value] } }\n\nputs result\n# \u51fa\u529b\u4f8b: {\"Category A\"=&gt;1000, \"Category B\"=&gt;1500, ...}<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-39\">2. \u30cd\u30b9\u30c8\u3057\u305fgroup_by<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u8907\u6570\u30ec\u30d9\u30eb\u306e\u30ab\u30c6\u30b4\u30ea\u3067\u30b0\u30eb\u30fc\u30d7\u5316\u3059\u308b\u4f8b<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">result = data.group_by { |item| item[:main_category] }\n             .transform_values { |items| items.group_by { |item| item[:sub_category] } }\n\nputs result\n# \u51fa\u529b\u4f8b: {\"Main Category A\"=&gt;{\"Sub Category X\"=&gt;[...], \"Sub Category Y\"=&gt;[...]}, ...}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-40\">\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306b\u304a\u3051\u308b\u9ad8\u5ea6\u306agroup_by\u306e\u4f7f\u7528\u4f8b<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u6700\u5f8c\u306b\u3001\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u4f7f\u7528\u3055\u308c\u308b\u53ef\u80fd\u6027\u306e\u3042\u308b\u3001\u3088\u308a\u8907\u96d1\u306a<code>group_by<\/code>\u306e\u4f7f\u7528\u4f8b\u3092\u898b\u3066\u307f\u307e\u3057\u3087\u3046\u3002<br>\u4ee5\u4e0b\u306f\u3001\u5927\u898f\u6a21\u306a\u30ed\u30b0\u30d5\u30a1\u30a4\u30eb\u3092\u89e3\u6790\u3059\u308b\u30b7\u30ca\u30ea\u30aa\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u5927\u898f\u6a21\u306a\u30ed\u30b0\u30d5\u30a1\u30a4\u30eb\u306e\u89e3\u6790\nlogs = File.readlines('large_log_file.txt', chomp: true)\n\nanalysis = logs.lazy\n  .map { |line| parse_log_line(line) }  # parse_log_line\u306f\u30ed\u30b0\u884c\u3092\u89e3\u6790\u3059\u308b\u4eee\u60f3\u306e\u30e1\u30bd\u30c3\u30c9\n  .group_by { |log| log[:error_type] }\n  .transform_values { |errors| errors.count }\n  .force\n\nputs analysis\n# \u51fa\u529b\u4f8b: {\"Error Type A\"=&gt;100, \"Error Type B\"=&gt;50, ...}<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u30b3\u30fc\u30c9\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u7279\u5fb4\u3092\u6301\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><code>lazy<\/code>\u3092\u4f7f\u7528\u3057\u3066\u9045\u5ef6\u8a55\u4fa1\u3092\u884c\u3044\u3001\u30e1\u30e2\u30ea\u52b9\u7387\u3092\u5411\u4e0a\u3055\u305b\u3066\u3044\u307e\u3059\u3002<\/li>\n\n\n\n<li><code>map<\/code>\u3067\u30ed\u30b0\u306e\u5404\u884c\u3092\u89e3\u6790\u3057\u3001\u69cb\u9020\u5316\u3055\u308c\u305f\u30c7\u30fc\u30bf\u306b\u5909\u63db\u3057\u3066\u3044\u307e\u3059\u3002<\/li>\n\n\n\n<li><code>group_by<\/code>\u3067\u30a8\u30e9\u30fc\u30bf\u30a4\u30d7\u3054\u3068\u306b\u30b0\u30eb\u30fc\u30d7\u5316\u3057\u3066\u3044\u307e\u3059\u3002<\/li>\n\n\n\n<li><code>transform_values<\/code>\u3067\u5404\u30a8\u30e9\u30fc\u30bf\u30a4\u30d7\u306e\u51fa\u73fe\u56de\u6570\u3092\u30ab\u30a6\u30f3\u30c8\u3057\u3066\u3044\u307e\u3059\u3002<\/li>\n\n\n\n<li>\u6700\u5f8c\u306b<code>force<\/code>\u3092\u547c\u3073\u51fa\u3057\u3066\u5b9f\u969b\u306e\u8a55\u4fa1\u3092\u884c\u3063\u3066\u3044\u307e\u3059\u3002<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u65b9\u6cd5\u306b\u3088\u308a\u3001\u975e\u5e38\u306b\u5927\u304d\u306a\u30ed\u30b0\u30d5\u30a1\u30a4\u30eb\u3067\u3082\u52b9\u7387\u7684\u306b\u89e3\u6790\u3092\u884c\u3046\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-41\">\u307e\u3068\u3081<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>group_by<\/code>\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u3068\u9ad8\u5ea6\u306a\u4f7f\u7528\u4f8b\u306b\u3064\u3044\u3066\u5b66\u3073\u307e\u3057\u305f\u3002<br>\u5927\u898f\u6a21\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u306e\u6271\u3044\u65b9\u3001\u30e1\u30e2\u30ea\u3068\u901f\u5ea6\u306e\u6700\u9069\u5316\u3001\u9ad8\u5ea6\u306a\u30c7\u30fc\u30bf\u5206\u6790\u30c6\u30af\u30cb\u30c3\u30af\u3001\u305d\u3057\u3066\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u306e\u5fdc\u7528\u4f8b\u3092\u898b\u3066\u304d\u307e\u3057\u305f\u3002<br>\u3053\u308c\u3089\u306e\u6280\u8853\u3092\u7fd2\u5f97\u3059\u308b\u3053\u3068\u3067\u3001Ruby\u3092\u4f7f\u3063\u305f\u52b9\u7387\u7684\u3067\u6d17\u7df4\u3055\u308c\u305f\u30c7\u30fc\u30bf\u51e6\u7406\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306f\u5358\u7d14\u306a\u30e1\u30bd\u30c3\u30c9\u306b\u898b\u3048\u3066\u3001\u5b9f\u306f\u975e\u5e38\u306b\u5965\u304c\u6df1\u3044\u30c4\u30fc\u30eb\u3067\u3059\u3002<br>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u610f\u8b58\u3057\u306a\u304c\u3089\u9069\u5207\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u51e6\u7406\u30bf\u30b9\u30af\u3092\u52b9\u7387\u7684\u306b\u89e3\u6c7a\u3067\u304d\u307e\u3059\u3002<br>\u4eca\u56de\u5b66\u3093\u3060\u30c6\u30af\u30cb\u30c3\u30af\u3092\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u6d3b\u7528\u3057\u3001\u3055\u3089\u306a\u308b\u6700\u9069\u5316\u306e\u53ef\u80fd\u6027\u3092\u63a2\u3063\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>group_by<\/code>\u3092\u4f7f\u3063\u305f\u5b9f\u8df5\u7684\u306a\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3059\u3002<br>\u5b9f\u969b\u306e\u30d3\u30b8\u30cd\u30b9\u30b7\u30fc\u30f3\u3067\u3069\u306e\u3088\u3046\u306b\u6d3b\u7528\u3067\u304d\u308b\u304b\u3001\u5177\u4f53\u7684\u306a\u4f8b\u3092\u901a\u3058\u3066\u5b66\u3093\u3067\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-sgb-headings sgb-heading\" id=\"i-42\"><span class=\"sgb-heading__inner sgb-heading--type1 with-icon\" style=\"background-color:transparent;border-color:transparent;font-size:1.2em\"><i class=\"fa fa-check\" style=\"color:var(--wp--preset--color--sango-main)\"><\/i><span class=\"sgb-heading__text\" style=\"color:#333\">5. \u5b9f\u8df5\u7684\u306a\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\uff1agroup_by\u3067\u89e3\u6c7a\u3059\u308b\u73fe\u5b9f\u4e16\u754c\u306e\u554f\u984c<\/span><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u5358\u306a\u308b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3067\u306f\u306a\u304f\u3001\u5b9f\u969b\u306e\u30d3\u30b8\u30cd\u30b9\u30b7\u30fc\u30f3\u3067\u76f4\u9762\u3059\u308b\u69d8\u3005\u306a\u554f\u984c\u3092\u52b9\u7387\u7684\u306b\u89e3\u6c7a\u3059\u308b\u30c4\u30fc\u30eb\u3067\u3059\u3002<br>\u3053\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>group_by<\/code>\u3092\u4f7f\u3063\u3066\u89e3\u6c7a\u3067\u304d\u308b\u73fe\u5b9f\u4e16\u754c\u306e\u554f\u984c\u3068\u305d\u306e\u5177\u4f53\u7684\u306a\u5b9f\u88c5\u65b9\u6cd5\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-43\">5.1 \u58f2\u4e0a\u30c7\u30fc\u30bf\u306e\u96c6\u8a08\uff1a\u65e5\u4ed8\u5225\u3001\u88fd\u54c1\u5225\u3001\u9867\u5ba2\u5225\u306e\u5206\u6790\u3092\u4e00\u767a\u3067<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u591a\u304f\u306e\u4f01\u696d\u306b\u3068\u3063\u3066\u3001\u58f2\u4e0a\u30c7\u30fc\u30bf\u306e\u5206\u6790\u306f\u91cd\u8981\u306a\u696d\u52d9\u306e\u4e00\u3064\u3067\u3059\u3002<br><code>group_by<\/code>\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u8907\u6570\u306e\u8ef8\u306b\u57fa\u3065\u3044\u305f\u9ad8\u5ea6\u306a\u5206\u6790\u3092\u7c21\u5358\u306b\u884c\u3046\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-44\">\u554f\u984c<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u65e5\u4ed8\u5225\u3001\u88fd\u54c1\u5225\u3001\u9867\u5ba2\u5225\u306e\u58f2\u4e0a\u3092\u5206\u6790\u3059\u308b\u5fc5\u8981\u304c\u3042\u308b\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-45\">\u89e3\u6c7a\u7b56<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">sales_data = [\n  {date: '2023-09-01', product: 'A', customer: 'X', amount: 100},\n  {date: '2023-09-01', product: 'B', customer: 'Y', amount: 150},\n  {date: '2023-09-02', product: 'A', customer: 'Z', amount: 200},\n  # ... more sales data\n]\n\nanalysis = sales_data.group_by { |sale| [sale[:date], sale[:product], sale[:customer]] }\n                     .transform_values { |sales| sales.sum { |sale| sale[:amount] } }\n\nputs analysis\n# \u51fa\u529b\u4f8b:\n# {\n#   ['2023-09-01', 'A', 'X'] =&gt; 100,\n#   ['2023-09-01', 'B', 'Y'] =&gt; 150,\n#   ['2023-09-02', 'A', 'Z'] =&gt; 200,\n#   ...\n# }<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u89e3\u6c7a\u7b56\u306e\u5229\u70b9<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u8907\u6570\u306e\u8ef8\uff08\u65e5\u4ed8\u3001\u88fd\u54c1\u3001\u9867\u5ba2\uff09\u3067\u306e\u58f2\u4e0a\u5206\u6790\u304c\u53ef\u80fd<\/li>\n\n\n\n<li>\u30c7\u30fc\u30bf\u306e\u96c6\u8a08\u304c\u7c21\u5358\u3067\u3001\u30b3\u30fc\u30c9\u304c\u7c21\u6f54<\/li>\n\n\n\n<li>\u58f2\u4e0a\u30c8\u30ec\u30f3\u30c9\u306e\u628a\u63e1\u304c\u5bb9\u6613<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-46\">5.2 \u30ed\u30b0\u30d5\u30a1\u30a4\u30eb\u306e\u89e3\u6790\uff1a\u30a8\u30e9\u30fc\u30bf\u30a4\u30d7\u5225\u306e\u51fa\u73fe\u983b\u5ea6\u3092group_by\u3067\u77ac\u6642\u306b\u628a\u63e1<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5927\u898f\u6a21\u306a\u30b7\u30b9\u30c6\u30e0\u306e\u904b\u7528\u3067\u306f\u3001\u30ed\u30b0\u30d5\u30a1\u30a4\u30eb\u306e\u52b9\u7387\u7684\u306a\u89e3\u6790\u304c\u4e0d\u53ef\u6b20\u3067\u3059\u3002<br><code>group_by<\/code>\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u5927\u91cf\u306e\u30ed\u30b0\u30c7\u30fc\u30bf\u304b\u3089\u91cd\u8981\u306a\u60c5\u5831\u3092\u7d20\u65e9\u304f\u62bd\u51fa\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-47\">\u554f\u984c<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u5927\u91cf\u306e\u30ed\u30b0\u30d5\u30a1\u30a4\u30eb\u304b\u3089\u30a8\u30e9\u30fc\u30bf\u30a4\u30d7\u5225\u306e\u51fa\u73fe\u983b\u5ea6\u3092\u628a\u63e1\u3057\u3001\u512a\u5148\u5ea6\u306e\u9ad8\u3044\u554f\u984c\u3092\u7279\u5b9a\u3059\u308b\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-48\">\u89e3\u6c7a\u7b56<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">logs = [\n  {timestamp: '2023-09-01 10:00:00', error_type: 'NetworkError', message: 'Connection timeout'},\n  {timestamp: '2023-09-01 10:05:00', error_type: 'DatabaseError', message: 'Query failed'},\n  {timestamp: '2023-09-01 10:10:00', error_type: 'NetworkError', message: 'DNS lookup failed'},\n  # ... more log entries\n]\n\nerror_analysis = logs.group_by { |log| log[:error_type] }\n                     .transform_values(&amp;:count)\n                     .sort_by { |_, count| -count }\n\nputs error_analysis\n# \u51fa\u529b\u4f8b:\n# [\n#   [\"NetworkError\", 2],\n#   [\"DatabaseError\", 1],\n#   ...\n# ]<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u89e3\u6c7a\u7b56\u306e\u5229\u70b9<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u30a8\u30e9\u30fc\u306e\u50be\u5411\u3092\u7d20\u65e9\u304f\u628a\u63e1\u3067\u304d\u308b<\/li>\n\n\n\n<li>\u512a\u5148\u5ea6\u306e\u9ad8\u3044\u554f\u984c\u306e\u7279\u5b9a\u304c\u5bb9\u6613<\/li>\n\n\n\n<li>\u5927\u91cf\u306e\u30ed\u30b0\u30c7\u30fc\u30bf\u3092\u52b9\u7387\u7684\u306b\u51e6\u7406\u3067\u304d\u308b<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-49\">5.3 \u305d\u306e\u4ed6\u306e\u5b9f\u8df5\u7684\u306a\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306e\u5fdc\u7528\u7bc4\u56f2\u306f\u5e83\u304f\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30b7\u30fc\u30f3\u3067\u3082\u6d3b\u7528\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-50\">\u9867\u5ba2\u30bb\u30b0\u30e1\u30f3\u30c6\u30fc\u30b7\u30e7\u30f3<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">customer_segments = customers.group_by { |c| [c[:age_group], c[:purchase_frequency]] }\n# \u5e74\u9f62\u5c64\u3068\u8cfc\u8cb7\u983b\u5ea6\u306b\u57fa\u3065\u3044\u3066\u9867\u5ba2\u3092\u30bb\u30b0\u30e1\u30f3\u30c8\u5316<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-51\">\u5728\u5eab\u7ba1\u7406<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">inventory_by_category = inventory.group_by { |item| item[:category] }\n                                 .transform_values { |items| items.sum { |item| item[:quantity] } }\n# \u30ab\u30c6\u30b4\u30ea\u30fc\u5225\u306e\u5728\u5eab\u6570\u3092\u96c6\u8a08<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-52\">\u5f93\u696d\u54e1\u306e\u30b9\u30ad\u30eb\u7ba1\u7406<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">skills_by_department = employees.group_by { |e| e[:department] }\n                                .transform_values { |emps| emps.flat_map { |e| e[:skills] }.uniq }\n# \u90e8\u7f72\u5225\u306e\u4fdd\u6709\u30b9\u30ad\u30eb\u30ea\u30b9\u30c8\u3092\u4f5c\u6210<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-53\">\u307e\u3068\u3081<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u308c\u3089\u306e\u4f8b\u304c\u793a\u3059\u3088\u3046\u306b\u3001<code>group_by<\/code>\u306f\u5358\u306a\u308b\u30c7\u30fc\u30bf\u306e\u30b0\u30eb\u30fc\u30d7\u5316\u4ee5\u4e0a\u306e\u529b\u3092\u6301\u3063\u3066\u3044\u307e\u3059\u3002<br>\u9069\u5207\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u8907\u96d1\u306a\u30d3\u30b8\u30cd\u30b9\u8981\u4ef6\u3092\u6e80\u305f\u3059\u30c7\u30fc\u30bf\u5206\u6790\u3084\u51e6\u7406\u3092\u52b9\u7387\u7684\u306b\u884c\u3046\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u306f\u3001\u3053\u308c\u3089\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3092\u7d44\u307f\u5408\u308f\u305b\u305f\u308a\u3001\u4ed6\u306eRuby\u30e1\u30bd\u30c3\u30c9\u3068\u9023\u643a\u3055\u305b\u305f\u308a\u3059\u308b\u3053\u3068\u3067\u3001\u3055\u3089\u306b\u9ad8\u5ea6\u306a\u5206\u6790\u3084\u51e6\u7406\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002<br><code>group_by<\/code>\u306e\u53ef\u80fd\u6027\u3092\u6700\u5927\u9650\u306b\u5f15\u304d\u51fa\u3057\u3001\u30c7\u30fc\u30bf\u99c6\u52d5\u306e\u610f\u601d\u6c7a\u5b9a\u3092\u30b5\u30dd\u30fc\u30c8\u3059\u308b\u5f37\u529b\u306a\u30c4\u30fc\u30eb\u3068\u3057\u3066\u6d3b\u7528\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>group_by<\/code>\u3092\u4f7f\u7528\u3059\u308b\u969b\u306b\u3088\u304f\u906d\u9047\u3059\u308b\u8ab2\u984c\u3068\u3001\u305d\u308c\u3089\u3092\u89e3\u6c7a\u3059\u308b\u305f\u3081\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-sgb-headings sgb-heading\" id=\"i-54\"><span class=\"sgb-heading__inner sgb-heading--type1 with-icon\" style=\"background-color:transparent;border-color:transparent;font-size:1.2em\"><i class=\"fa fa-check\" style=\"color:var(--wp--preset--color--sango-main)\"><\/i><span class=\"sgb-heading__text\" style=\"color:#333\">6. group_by\u30de\u30b9\u30bf\u30fc\u3078\u306e\u9053\uff1a\u3088\u304f\u3042\u308b\u843d\u3068\u3057\u7a74\u3068\u89e3\u6c7a\u7b56<\/span><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306f\u5f37\u529b\u306a\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u304c\u3001\u4f7f\u7528\u3059\u308b\u969b\u306b\u306f\u3044\u304f\u3064\u304b\u306e\u843d\u3068\u3057\u7a74\u306b\u6ce8\u610f\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<br>\u3053\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3088\u304f\u3042\u308b\u554f\u984c\u3068\u305d\u306e\u89e3\u6c7a\u7b56\u3092\u7d39\u4ecb\u3057\u3001<code>group_by<\/code>\u306e\u30de\u30b9\u30bf\u30fc\u3078\u306e\u9053\u3092\u6b69\u3080\u305f\u3081\u306e\u77e5\u6075\u3092\u5171\u6709\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-55\">6.1 nil\u5024\u3084\u6b20\u640d\u30c7\u30fc\u30bf\u306e\u6271\u3044\uff1agroup_by\u3067\u306e\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u5bfe\u7b56<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-56\">\u554f\u984c<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">nil\u5024\u3084\u6b20\u640d\u30c7\u30fc\u30bf\u304c\u30b0\u30eb\u30fc\u30d7\u5316\u306e\u30ad\u30fc\u306b\u542b\u307e\u308c\u308b\u3068\u3001\u4e88\u671f\u3057\u306a\u3044\u7d50\u679c\u3092\u62db\u304f\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-57\">\u89e3\u6c7a\u7b56<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">data = [\n  {category: 'A', value: 10},\n  {category: nil, value: 20},\n  {category: 'B', value: 30}\n]\n\nresult = data.group_by { |item| item[:category] || 'Unknown' }\n\nputs result\n# \u51fa\u529b:\n# {\n#   \"A\" =&gt; [{category: \"A\", value: 10}],\n#   \"Unknown\" =&gt; [{category: nil, value: 20}],\n#   \"B\" =&gt; [{category: \"B\", value: 30}]\n# }<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u65b9\u6cd5\u3067\u306f\u3001nil\u306e\u4ee3\u308f\u308a\u306b\u2019Unknown\u2019\u306a\u3069\u306e\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u3092\u9069\u5207\u306b\u51e6\u7406\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-58\">6.2 \u30d6\u30ed\u30c3\u30af\u30d1\u30e9\u30e1\u30fc\u30bf\u306e\u7406\u89e3\u4e0d\u8db3\u306b\u3088\u308b\u610f\u56f3\u3057\u306a\u3044\u7d50\u679c\u306e\u56de\u907f\u65b9\u6cd5<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-59\">\u554f\u984c<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u30d6\u30ed\u30c3\u30af\u30d1\u30e9\u30e1\u30fc\u30bf\u306e\u7406\u89e3\u4e0d\u8db3\u306b\u3088\u308a\u3001\u610f\u56f3\u3057\u306a\u3044\u30b0\u30eb\u30fc\u30d7\u5316\u304c\u8d77\u3053\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-60\">\u4f8b\u3068\u89e3\u6c7a\u7b56<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\ndata = [{value: 80}, {value: 120}, {value: 90}]\nresult = data.group_by { |item| item[:value] &gt; 100 }\nputs result\n# \u51fa\u529b: {false=&gt;[{value: 80}, {value: 90}], true=&gt;[{value: 120}]}\n\n# \u6539\u5584\u3055\u308c\u305f\u30b3\u30fc\u30c9\nbetter_result = data.group_by { |item| item[:value] &gt; 100 ? 'High' : 'Low' }\nputs better_result\n# \u51fa\u529b: {\"Low\"=&gt;[{value: 80}, {value: 90}], \"High\"=&gt;[{value: 120}]}<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u771f\u507d\u5024\u3067\u306f\u306a\u304f\u3001\u660e\u793a\u7684\u306a\u30b0\u30eb\u30fc\u30d7\u540d\u3092\u8fd4\u3059\u3088\u3046\u306b\u3059\u308b\u3053\u3068\u3067\u3001\u7d50\u679c\u304c\u3088\u308a\u76f4\u611f\u7684\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-61\">6.3 \u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u554f\u984c\u3068\u6700\u9069\u5316\u65b9\u6cd5<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5927\u898f\u6a21\u306a\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3092\u6271\u3046\u969b\u3001\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u304c\u6025\u5897\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-62\">\u89e3\u6c7a\u7b56\uff1a\u30d0\u30c3\u30c1\u51e6\u7406<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">result = data.each_slice(1000).with_object({}) do |slice, result|\n  slice.group_by { |item| item[:category] }.each do |category, items|\n    result ||= []\n    result.concat(items)\n  end\nend<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u65b9\u6cd5\u3067\u306f\u3001\u30c7\u30fc\u30bf\u3092\u30d0\u30c3\u30c1\u3067\u51e6\u7406\u3057\u3001\u7d50\u679c\u3092\u5f90\u3005\u306b\u69cb\u7bc9\u3059\u308b\u3053\u3068\u3067\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u6291\u3048\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-63\">6.4 \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u95a2\u3059\u308b\u8003\u616e\u4e8b\u9805\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-64\">1. <strong>\u30b7\u30f3\u30d7\u30eb\u306a\u30ad\u30fc\u751f\u6210\u3092\u5fc3\u304c\u3051\u308b<\/strong><\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u8907\u96d1\u306a\u30d6\u30ed\u30c3\u30af\u51e6\u7406\u306f\u907f\u3051\u3001\u53ef\u80fd\u306a\u9650\u308a\u30b7\u30f3\u30d7\u30eb\u306a\u30ad\u30fc\u751f\u6210\u30ed\u30b8\u30c3\u30af\u3092\u4f7f\u7528\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-65\">2. <strong>\u4e8b\u524d\u30bd\u30fc\u30c8\u306e\u6d3b\u7528<\/strong><\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u5927\u898f\u6a21\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3067\u306f\u3001<code>group_by<\/code>\u306e\u524d\u306b\u30c7\u30fc\u30bf\u3092\u30bd\u30fc\u30c8\u3059\u308b\u3053\u3068\u3067\u3001\u51e6\u7406\u901f\u5ea6\u304c\u5411\u4e0a\u3059\u308b\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   sorted_data = data.sort_by { |item| item[:category] }\n   result = sorted_data.group_by { |item| item[:category] }<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-66\">3. <strong>\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\u306e\u6d3b\u7528<\/strong><\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u5fc5\u8981\u306b\u5fdc\u3058\u3066\u3001<code>group_by<\/code>\u306e\u524d\u306b<code>select<\/code>\u3084<code>reject<\/code>\u3092\u4f7f\u7528\u3057\u3066\u30c7\u30fc\u30bf\u3092\u7d5e\u308a\u8fbc\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   filtered_result = data.select { |item| item[:value] &gt; 0 }\n                         .group_by { |item| item[:category] }<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-67\">6.5 group_by\u4f7f\u7528\u6642\u306e\u30c7\u30d0\u30c3\u30b0\u306e\u30b3\u30c4<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-68\">1. <strong>\u5c0f\u3055\u306a\u30b5\u30f3\u30d7\u30eb\u30c7\u30fc\u30bf\u3067\u30c6\u30b9\u30c8<\/strong><\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u672c\u756a\u30c7\u30fc\u30bf\u306e\u524d\u306b\u3001\u5c0f\u898f\u6a21\u306a\u30b5\u30f3\u30d7\u30eb\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u3067\u30ed\u30b8\u30c3\u30af\u3092\u30c6\u30b9\u30c8\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-69\">2. <strong>\u4e2d\u9593\u7d50\u679c\u306e\u78ba\u8a8d<\/strong><\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u8907\u96d1\u306a<code>group_by<\/code>\u64cd\u4f5c\u3067\u306f\u3001\u4e2d\u9593\u7d50\u679c\u3092\u51fa\u529b\u3057\u3066\u51e6\u7406\u306e\u6d41\u308c\u3092\u78ba\u8a8d\u3059\u308b\u3053\u3068\u304c\u6709\u52b9\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   result = data.group_by do |item|\n     puts \"Processing: #{item}\"  # \u30c7\u30d0\u30c3\u30b0\u51fa\u529b\n     item[:category]\n   end<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-70\">3. <strong>\u5358\u4f53\u30c6\u30b9\u30c8\u306e\u6d3b\u7528<\/strong><\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u3092\u542b\u3080\u69d8\u3005\u306a\u30b7\u30ca\u30ea\u30aa\u3092\u30ab\u30d0\u30fc\u3059\u308b\u5358\u4f53\u30c6\u30b9\u30c8\u3092\u66f8\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-71\">4. <strong>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30d7\u30ed\u30d5\u30a1\u30a4\u30ea\u30f3\u30b0<\/strong><\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">Ruby\u306e\u30d7\u30ed\u30d5\u30a1\u30a4\u30ea\u30f3\u30b0\u30c4\u30fc\u30eb\u3092\u4f7f\u7528\u3057\u3066\u3001\u30dc\u30c8\u30eb\u30cd\u30c3\u30af\u3092\u7279\u5b9a\u3057\u3001\u6700\u9069\u5316\u306e\u6a5f\u4f1a\u3092\u898b\u3064\u3051\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u308c\u3089\u306e\u843d\u3068\u3057\u7a74\u3092\u7406\u89e3\u3057\u3001\u9069\u5207\u306b\u5bfe\u51e6\u3059\u308b\u3053\u3068\u3067\u3001<code>group_by<\/code>\u3092\u3088\u308a\u52b9\u679c\u7684\u306b\u4f7f\u7528\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<br>\u5e38\u306b\u7d50\u679c\u3092\u691c\u8a3c\u3057\u3001\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u3092\u8003\u616e\u3059\u308b\u3053\u3068\u3092\u5fd8\u308c\u305a\u306b\u3001<code>group_by<\/code>\u30de\u30b9\u30bf\u30fc\u3078\u306e\u9053\u3092\u6b69\u3093\u3067\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-sgb-headings sgb-heading\" id=\"i-72\"><span class=\"sgb-heading__inner sgb-heading--type1 with-icon\" style=\"background-color:transparent;border-color:transparent;font-size:1.2em\"><i class=\"fa fa-check\" style=\"color:var(--wp--preset--color--sango-main)\"><\/i><span class=\"sgb-heading__text\" style=\"color:#333\">7. \u6b21\u306e\u30b9\u30c6\u30c3\u30d7\uff1agroup_by\u3092\u8d85\u3048\u305f\u9ad8\u5ea6\u306a\u30c7\u30fc\u30bf\u51e6\u7406\u6280\u6cd5<\/span><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u30e1\u30bd\u30c3\u30c9\u306e\u7406\u89e3\u3092\u6df1\u3081\u305f\u3068\u3053\u308d\u3067\u3001\u3055\u3089\u306b\u9ad8\u5ea6\u306a\u30c7\u30fc\u30bf\u51e6\u7406\u6280\u6cd5\u3078\u3068\u6b69\u3092\u9032\u3081\u307e\u3057\u3087\u3046\u3002<br>\u3053\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>group_by<\/code>\u3092\u8db3\u304c\u304b\u308a\u306b\u3001\u3088\u308a\u6d17\u7df4\u3055\u308c\u305fRuby\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u4e16\u754c\u3078\u8a98\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-73\">7.1 group_by\u304b\u3089\u59cb\u3081\u308b\u95a2\u6570\u578b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u5165\u9580<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306f\u95a2\u6570\u578b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u6982\u5ff5\u3092\u53d6\u308a\u5165\u308c\u3066\u3044\u307e\u3059\u3002<br>\u95a2\u6570\u578b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u4e3b\u8981\u306a\u6982\u5ff5\u306b\u306f\u3001\u4e0d\u5909\u6027\u3001\u7d14\u7c8b\u95a2\u6570\u3001\u9ad8\u968e\u95a2\u6570\u3001\u9045\u5ef6\u8a55\u4fa1\u306a\u3069\u304c\u3042\u308a\u307e\u3059\u3002<br>\u4ee5\u4e0b\u306e\u4f8b\u3067\u3001\u3053\u308c\u3089\u306e\u6982\u5ff5\u304cRuby\u3067\u3069\u306e\u3088\u3046\u306b\u5b9f\u73fe\u3055\u308c\u3066\u3044\u308b\u304b\u3092\u898b\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">result = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10].lazy\n                                        .map { |n| n * 2 }\n                                        .select(&amp;:even?)\n                                        .take(5)\n                                        .force\n\nputs result\n# \u51fa\u529b: [2, 4, 6, 8, 10]<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u4f8b\u3067\u306f\u3001<code>lazy<\/code>\u306b\u3088\u308b\u9045\u5ef6\u8a55\u4fa1\u3001<code>map<\/code>\u3084<code>select<\/code>\u306b\u3088\u308b\u9ad8\u968e\u95a2\u6570\u306e\u4f7f\u7528\u3001\u305d\u3057\u3066\u4e0d\u5909\u306e\u64cd\u4f5c\u30c1\u30a7\u30fc\u30f3\u3092\u898b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-74\">7.2 \u30c7\u30fc\u30bf\u30b5\u30a4\u30a8\u30f3\u30b9\u3068Ruby\uff1agroup_by\u3092\u6d3b\u7528\u3057\u305f\u7d71\u8a08\u51e6\u7406\u306e\u57fa\u790e<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306f\u30c7\u30fc\u30bf\u30b5\u30a4\u30a8\u30f3\u30b9\u306e\u57fa\u672c\u7684\u306a\u30bf\u30b9\u30af\u306b\u3082\u5fdc\u7528\u3067\u304d\u307e\u3059\u3002\u4ee5\u4e0b\u306b\u3001\u3044\u304f\u3064\u304b\u306e\u4f8b\u3092\u793a\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-75\">1. <strong>\u8a18\u8ff0\u7d71\u8a08\u91cf\u306e\u8a08\u7b97<\/strong><\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   data.group_by { |item| item[:category] }\n       .transform_values { |values| values.sum { |v| v[:amount] } }<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-76\">2. <strong>\u30c7\u30fc\u30bf\u306e\u30d3\u30cb\u30f3\u30b0\uff08binning\uff09<\/strong><\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   ages = [22, 35, 27, 41, 59, 33, 45]\n   age_groups = ages.group_by { |age| age \/ 10 * 10 }\n   puts age_groups\n   # \u51fa\u529b: {20=&gt;[22, 27], 30=&gt;[35, 33], 40=&gt;[41, 45], 50=&gt;[59]}<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-77\">3. <strong>\u6642\u7cfb\u5217\u30c7\u30fc\u30bf\u306e\u5206\u6790<\/strong><\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   time_series_data.group_by { |data| data[:timestamp].strftime('%Y-%m') }\n                   .transform_values { |values| values.sum { |v| v[:value] } }<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-78\">7.3 \u8907\u96d1\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u306b\u5bfe\u3059\u308bgroup_by\u306e\u5fdc\u7528<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u3088\u308a\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u306b\u5bfe\u3057\u3066\u3082\u3001<code>group_by<\/code>\u306f\u52b9\u679c\u7684\u306b\u4f7f\u7528\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">nested_data = [\n  {category: {main: 'Electronics', sub: 'Phones'}, price: 500},\n  {category: {main: 'Electronics', sub: 'Laptops'}, price: 1000},\n  {category: {main: 'Books', sub: 'Fiction'}, price: 15}\n]\n\nresult = nested_data.group_by { |item| item.dig(:category, :main) }\nputs result\n# \u51fa\u529b:\n# {\n#   \"Electronics\"=&gt;[\n#     {:category=&gt;{:main=&gt;\"Electronics\", :sub=&gt;\"Phones\"}, :price=&gt;500},\n#     {:category=&gt;{:main=&gt;\"Electronics\", :sub=&gt;\"Laptops\"}, :price=&gt;1000}\n#   ],\n#   \"Books\"=&gt;[\n#     {:category=&gt;{:main=&gt;\"Books\", :sub=&gt;\"Fiction\"}, :price=&gt;15}\n#   ]\n# }<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-79\">7.4 \u3055\u3089\u306a\u308b\u9ad8\u307f\u3078\uff1a\u4eca\u5f8c\u306e\u5b66\u7fd2\u65b9\u5411\u6027<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306e\u7406\u89e3\u3092\u6df1\u3081\u305f\u5f8c\u306f\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u5206\u91ce\u306b\u30c1\u30e3\u30ec\u30f3\u30b8\u3057\u3066\u307f\u308b\u306e\u3082\u3088\u3044\u3067\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u9ad8\u5ea6\u306aRuby\u30e1\u30bf\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0<\/li>\n\n\n\n<li>\u4e26\u5217\u51e6\u7406\u3068<code>group_by<\/code>\u306e\u7d44\u307f\u5408\u308f\u305b<\/li>\n\n\n\n<li>\u6a5f\u68b0\u5b66\u7fd2\u30a2\u30eb\u30b4\u30ea\u30ba\u30e0\u306eRuby\u3067\u306e\u5b9f\u88c5<\/li>\n\n\n\n<li>\u5927\u898f\u6a21\u30c7\u30fc\u30bf\u51e6\u7406\u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af\uff08\u4f8b\uff1aApache Spark\uff09\u3068\u306e\u9023\u643a<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u308c\u3089\u306e\u5206\u91ce\u3092\u5b66\u3076\u3053\u3068\u3067\u3001Ruby\u3092\u4f7f\u3063\u305f\u30c7\u30fc\u30bf\u51e6\u7406\u306e\u30b9\u30ad\u30eb\u3092\u3055\u3089\u306b\u5411\u4e0a\u3055\u305b\u3001\u3088\u308a\u8907\u96d1\u306a\u554f\u984c\u306b\u53d6\u308a\u7d44\u3080\u6e96\u5099\u304c\u6574\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>group_by<\/code>\u306f\u5358\u306a\u308b\u59cb\u307e\u308a\u306b\u904e\u304e\u307e\u305b\u3093\u3002<br>Ruby\u306e\u8c4a\u304b\u306a\u8868\u73fe\u529b\u3068\u67d4\u8edf\u6027\u3092\u6d3b\u304b\u3057\u3001\u30c7\u30fc\u30bf\u51e6\u7406\u306e\u65b0\u305f\u306a\u5730\u5e73\u3092\u5207\u308a\u958b\u3044\u3066\u3044\u3063\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Ruby\u306egroup_by\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u30c7\u30fc\u30bf\u51e6\u7406\u306e\u5f37\u529b\u306a\u5473\u65b9\u3067\u3059\u3002\u914d\u5217\u3084\u30cf\u30c3\u30b7\u30e5\u3092\u81ea\u5728\u306b\u64cd\u308a\u3001\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u3092\u7c21\u5358\u306b\u6574\u7406\u3067\u304d\u308b\u3001\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u306e\u4f7f\u3044\u65b9\u3092\u30de\u30b9\u30bf\u30fc\u3059\u308c\u3070\u3001\u3042\u306a\u305f\u306eRuby\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u30b9\u30ad\u30eb\u306f\u4e00\u6c17\u306b\u5411\u4e0a\u3059\u308b &#8230; <\/p>\n","protected":false},"author":1,"featured_media":3094,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,65],"tags":[],"class_list":["post-136","post","type-post","status-publish","format-standard","has-post-thumbnail","category-ruby","category-ruby-syntax"],"_links":{"self":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/136","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=136"}],"version-history":[{"count":1,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/136\/revisions"}],"predecessor-version":[{"id":137,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/136\/revisions\/137"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/media\/3094"}],"wp:attachment":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=136"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=136"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=136"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}