{"id":1336,"date":"2025-03-24T08:52:19","date_gmt":"2025-03-23T23:52:19","guid":{"rendered":"https:\/\/dexall.co.jp\/articles\/?p=1336"},"modified":"2025-03-24T08:52:19","modified_gmt":"2025-03-23T23:52:19","slug":"%e3%80%90%e4%bf%9d%e5%ad%98%e7%89%88%e3%80%91ruby%e3%81%aemap%e3%83%a1%e3%82%bd%e3%83%83%e3%83%89%e5%ae%8c%e5%85%a8%e3%83%9e%e3%82%b9%e3%82%bf%e3%83%bc%ef%bc%81%e5%9f%ba%e7%a4%8e%e3%81%8b%e3%82%89","status":"publish","type":"post","link":"https:\/\/dexall.co.jp\/articles\/?p=1336","title":{"rendered":"\u3010\u4fdd\u5b58\u7248\u3011Ruby\u306emap\u30e1\u30bd\u30c3\u30c9\u5b8c\u5168\u30de\u30b9\u30bf\u30fc\uff01\u57fa\u790e\u304b\u3089\u5b9f\u8df5\u307e\u3067\u89e3\u8aac\u3059\u308b7\u3064\u306e\u6d3b\u7528\u6cd5"},"content":{"rendered":"\n<h1 class=\"wp-block-heading\" id=\"i-0\">Ruby\u306emap\u30e1\u30bd\u30c3\u30c9\u3068\u306f\uff1f\u521d\u5fc3\u8005\u3067\u3082\u308f\u304b\u308b\u57fa\u790e\u77e5\u8b58<\/h1>\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\">Ruby\u306emap\u30e1\u30bd\u30c3\u30c9\u3068\u306f\uff1f\u521d\u5fc3\u8005\u3067\u3082\u308f\u304b\u308b\u57fa\u790e\u77e5\u8b58<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-1\">\u914d\u5217\u306e\u8981\u7d20\u3092\u4e00\u62ec\u5909\u63db\u3067\u304d\u308b\u4fbf\u5229\u306a\u30e1\u30bd\u30c3\u30c9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-2\">each vs map\uff1a\u623b\u308a\u5024\u306e\u9055\u3044\u3092\u7406\u89e3\u3057\u3088\u3046<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-6\">map\u30e1\u30bd\u30c3\u30c9\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3092\u30de\u30b9\u30bf\u30fc\u3057\u3088\u3046<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-7\">\u6587\u5b57\u5217\u914d\u5217\u306e\u5909\u63db\u4f8b\u3067\u5b66\u3076map<\/a>      <\/li>      <li>        <a href=\"#i-8\">\u6570\u5024\u8a08\u7b97\u3067\u6d3b\u7528\u3059\u308bmap\u306e\u4f7f\u3044\u65b9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-9\">\u30d6\u30ed\u30c3\u30af\u8a18\u6cd5\u306e\u9055\u3044\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-13\">\u77e5\u3063\u3066\u304a\u304f\u3079\u304dmap\u306e\u5fdc\u7528\u30c6\u30af\u30cb\u30c3\u30af<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-14\">\u30cf\u30c3\u30b7\u30e5\u306b\u5bfe\u3059\u308bmap\u306e\u6d3b\u7528\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-15\">\u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3\u3067\u30b9\u30de\u30fc\u30c8\u306b\u66f8\u304f\u65b9\u6cd5<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-16\">nil\u5bfe\u7b56\u3068map!\u306e\u4f7f\u3044\u5206\u3051<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-19\">\u5b9f\u8df5\u7684\u306a\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u3067\u5b66\u3076map\u6d3b\u7528\u8853<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-20\">API\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u30c7\u30fc\u30bf\u6574\u5f62\u30c6\u30af\u30cb\u30c3\u30af<\/a>      <\/li>      <li>        <a href=\"#i-21\">\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u53d6\u5f97\u3057\u305f\u30ec\u30b3\u30fc\u30c9\u306e\u5909\u63db\u4f8b<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-22\">CSV\u30c7\u30fc\u30bf\u51e6\u7406\u3067\u306e\u6d3b\u7528\u65b9\u6cd5<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-23\">map\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u6700\u9069\u5316\u3059\u308b\u30b3\u30c4<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-24\">\u5927\u91cf\u30c7\u30fc\u30bf\u51e6\u7406\u6642\u306e\u6ce8\u610f\u70b9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-25\">\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u6291\u3048\u308b\u30c6\u30af\u30cb\u30c3\u30af<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-27\">\u3088\u304f\u3042\u308b\u9593\u9055\u3044\u3068\u89e3\u6c7a\u65b9\u6cd5<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-28\">\u7834\u58ca\u7684\u30e1\u30bd\u30c3\u30c9\u3067\u30cf\u30de\u308b\u30b1\u30fc\u30b9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-29\">\u30b9\u30b3\u30fc\u30d7\u306e\u52d8\u9055\u3044\u306b\u3088\u308b\u30d0\u30b0<\/a>      <\/li>    <\/ul>  <\/li>  <li class=\"last\">    <a href=\"#i-31\">\u4ee3\u66ff\u624b\u6bb5\u3068\u306e\u6bd4\u8f03\u3067\u308f\u304b\u308bmap\u306e\u4f7f\u3044\u3069\u3053\u308d<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-32\">collect\u3001map\u3001transform\u306e\u9055\u3044<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-33\">map\u3068inject\/reduce\u306e\u4f7f\u3044\u5206\u3051<\/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-heading\" id=\"i-1\">\u914d\u5217\u306e\u8981\u7d20\u3092\u4e00\u62ec\u5909\u63db\u3067\u304d\u308b\u4fbf\u5229\u306a\u30e1\u30bd\u30c3\u30c9<\/h2>\n\n\n\n<p><code>map<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u914d\u5217\u306e\u5404\u8981\u7d20\u306b\u5bfe\u3057\u3066\u540c\u3058\u51e6\u7406\u3092\u9069\u7528\u3057\u3001\u305d\u306e\u7d50\u679c\u304b\u3089\u65b0\u3057\u3044\u914d\u5217\u3092\u4f5c\u6210\u3059\u308b\u975e\u5e38\u306b\u5f37\u529b\u306a\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002\u914d\u5217\u64cd\u4f5c\u306e\u57fa\u672c\u7684\u306a\u30e1\u30bd\u30c3\u30c9\u306e1\u3064\u3067\u3001\u30c7\u30fc\u30bf\u5909\u63db\u306e\u5834\u9762\u3067\u983b\u7e41\u306b\u4f7f\u7528\u3055\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u4ee5\u4e0b\u306e\u4f8b\u3067\u5177\u4f53\u7684\u306b\u898b\u3066\u307f\u307e\u3057\u3087\u3046\uff1a<\/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]\ndoubled = numbers.map { |n| n * 2 }\nputs doubled  # \u51fa\u529b: [2, 4, 6, 8, 10]<\/pre>\n\n\n\n<p>\u3053\u306e\u30b3\u30fc\u30c9\u3067\u306f\u3001\u5143\u306e\u914d\u5217<code>numbers<\/code>\u306e\u5404\u8981\u7d20\u30922\u500d\u306b\u3057\u305f\u65b0\u3057\u3044\u914d\u5217\u304c\u4f5c\u6210\u3055\u308c\u307e\u3059\u3002\u5143\u306e\u914d\u5217\u306f\u305d\u306e\u307e\u307e\u4fdd\u6301\u3055\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-2\">each vs map\uff1a\u623b\u308a\u5024\u306e\u9055\u3044\u3092\u7406\u89e3\u3057\u3088\u3046<\/h2>\n\n\n\n<p>\u521d\u5fc3\u8005\u304c\u3088\u304f\u6df7\u4e71\u3059\u308b\u306e\u304c\u3001<code>each<\/code>\u30e1\u30bd\u30c3\u30c9\u3068<code>map<\/code>\u30e1\u30bd\u30c3\u30c9\u306e\u9055\u3044\u3067\u3059\u3002\u4e21\u8005\u306e\u4e3b\u306a\u9055\u3044\u306f\u300c\u623b\u308a\u5024\u300d\u306b\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-3\">each\u30e1\u30bd\u30c3\u30c9\u306e\u7279\u5fb4<\/h3>\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]\nresult_each = numbers.each { |n| n * 2 }\nputs numbers      # \u51fa\u529b: [1, 2, 3]\nputs result_each  # \u51fa\u529b: [1, 2, 3]<\/pre>\n\n\n\n<p><code>each<\/code>\u306f\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5143\u306e\u914d\u5217\u3092\u305d\u306e\u307e\u307e\u8fd4\u3059<\/li>\n\n\n\n<li>\u30d6\u30ed\u30c3\u30af\u5185\u306e\u51e6\u7406\u7d50\u679c\u306f\u623b\u308a\u5024\u3068\u3057\u3066\u4f7f\u7528\u3055\u308c\u306a\u3044<\/li>\n\n\n\n<li>\u914d\u5217\u306e\u8981\u7d20\u3092\u9806\u756a\u306b\u51e6\u7406\u3059\u308b\u3060\u3051<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-4\">map\u30e1\u30bd\u30c3\u30c9\u306e\u7279\u5fb4<\/h3>\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]\nresult_map = numbers.map { |n| n * 2 }\nputs numbers      # \u51fa\u529b: [1, 2, 3]\nputs result_map   # \u51fa\u529b: [2, 4, 6]<\/pre>\n\n\n\n<p><code>map<\/code>\u306f\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u30d6\u30ed\u30c3\u30af\u5185\u306e\u51e6\u7406\u7d50\u679c\u304b\u3089\u65b0\u3057\u3044\u914d\u5217\u3092\u4f5c\u6210<\/li>\n\n\n\n<li>\u5143\u306e\u914d\u5217\u306f\u5909\u66f4\u3055\u308c\u306a\u3044<\/li>\n\n\n\n<li>\u5404\u8981\u7d20\u306e\u5909\u63db\u7d50\u679c\u304c\u65b0\u3057\u3044\u914d\u5217\u306e\u8981\u7d20\u3068\u306a\u308b<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-5\">\u4f7f\u3044\u5206\u3051\u306e\u30dd\u30a4\u30f3\u30c8<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30c7\u30fc\u30bf\u5909\u63db\u304c\u5fc5\u8981\u306a\u5834\u5408\u306f<code>map<\/code>\u3092\u4f7f\u3046<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u914d\u5217\u306e\u8981\u7d20\u3092\u5225\u306e\u5f62\u5f0f\u306b\u5909\u63db\u3057\u305f\u3044<\/li>\n\n\n\n<li>\u8a08\u7b97\u7d50\u679c\u306e\u914d\u5217\u304c\u5fc5\u8981<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u5358\u7d14\u306a\u7e70\u308a\u8fd4\u3057\u51e6\u7406\u306e\u5834\u5408\u306f<code>each<\/code>\u3092\u4f7f\u3046<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u914d\u5217\u306e\u8981\u7d20\u3092\u8868\u793a\u3059\u308b\u3060\u3051<\/li>\n\n\n\n<li>\u526f\u4f5c\u7528\uff08\u30d5\u30a1\u30a4\u30eb\u66f8\u304d\u8fbc\u307f\u306a\u3069\uff09\u304c\u76ee\u7684<\/li>\n<\/ul>\n\n\n\n<p>\u3053\u306e\u9055\u3044\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u9069\u5207\u306a\u30e1\u30bd\u30c3\u30c9\u3092\u9078\u629e\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<code>map<\/code>\u306f\u95a2\u6570\u578b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u8003\u3048\u65b9\u3092\u53d6\u308a\u5165\u308c\u305f\u3001\u3088\u308a\u5ba3\u8a00\u7684\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u308b\u30e1\u30bd\u30c3\u30c9\u3068\u8a00\u3048\u307e\u3059\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-6\">map\u30e1\u30bd\u30c3\u30c9\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3092\u30de\u30b9\u30bf\u30fc\u3057\u3088\u3046<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-7\">\u6587\u5b57\u5217\u914d\u5217\u306e\u5909\u63db\u4f8b\u3067\u5b66\u3076map<\/h2>\n\n\n\n<p>\u6587\u5b57\u5217\u51e6\u7406\u306f\u5b9f\u52d9\u3067\u3088\u304f\u4f7f\u3046\u30b1\u30fc\u30b9\u306e1\u3064\u3067\u3059\u3002\u4ee5\u4e0b\u306b\u5b9f\u8df5\u7684\u306a\u4f8b\u3092\u793a\u3057\u307e\u3059\uff1a<\/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=\"\"># \u6587\u5b57\u5217\u306e\u5927\u6587\u5b57\u5909\u63db\nnames = ['alice', 'bob', 'carol']\nupper_names = names.map { |name| name.upcase }\nputs upper_names  # \u51fa\u529b: [\"ALICE\", \"BOB\", \"CAROL\"]\n\n# \u6587\u5b57\u5217\u306e\u52a0\u5de5\uff08\u656c\u79f0\u8ffd\u52a0\uff09\nnames = ['\u7530\u4e2d', '\u9234\u6728', '\u4f50\u85e4']\nformatted_names = names.map { |name| \"#{name}\u69d8\" }\nputs formatted_names  # \u51fa\u529b: [\"\u7530\u4e2d\u69d8\", \"\u9234\u6728\u69d8\", \"\u4f50\u85e4\u69d8\"]\n\n# \u6587\u5b57\u5217\u304b\u3089\u7279\u5b9a\u306e\u60c5\u5831\u3092\u62bd\u51fa\nemails = ['user1@example.com', 'user2@example.com']\nusernames = emails.map { |email| email.split('@').first }\nputs usernames  # \u51fa\u529b: [\"user1\", \"user2\"]<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-8\">\u6570\u5024\u8a08\u7b97\u3067\u6d3b\u7528\u3059\u308bmap\u306e\u4f7f\u3044\u65b9<\/h2>\n\n\n\n<p>\u6570\u5024\u914d\u5217\u306e\u51e6\u7406\u3082<code>map<\/code>\u306e\u5f97\u610f\u5206\u91ce\u3067\u3059\uff1a<\/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=\"\"># \u57fa\u672c\u7684\u306a\u6570\u5024\u8a08\u7b97\nnumbers = [1, 2, 3, 4, 5]\nsquared = numbers.map { |n| n ** 2 }\nputs squared  # \u51fa\u529b: [1, 4, 9, 16, 25]\n\n# \u8907\u6570\u306e\u5024\u3092\u4f7f\u3063\u305f\u8a08\u7b97\nprices = [100, 200, 300]\ntax_rate = 0.1\nprices_with_tax = prices.map { |price| price * (1 + tax_rate) }\nputs prices_with_tax  # \u51fa\u529b: [110.0, 220.0, 330.0]\n\n# \u6761\u4ef6\u5206\u5c90\u3092\u542b\u3080\u8a08\u7b97\nscores = [85, 60, 95, 40, 78]\ngrades = scores.map do |score|\n  case\n  when score &gt;= 90 then 'A'\n  when score &gt;= 80 then 'B'\n  when score &gt;= 70 then 'C'\n  else 'D'\n  end\nend\nputs grades  # \u51fa\u529b: [\"B\", \"D\", \"A\", \"D\", \"C\"]<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-9\">\u30d6\u30ed\u30c3\u30af\u8a18\u6cd5\u306e\u9055\u3044\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h2>\n\n\n\n<p>Ruby\u3067\u306f2\u7a2e\u985e\u306e\u30d6\u30ed\u30c3\u30af\u8a18\u6cd5\u304c\u4f7f\u3048\u307e\u3059\uff1a<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-10\">1. \u6ce2\u62ec\u5f27\u3092\u4f7f\u3046\u65b9\u6cd5<\/h3>\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=\"\"># 1\u884c\u3067\u53ce\u307e\u308b\u7c21\u5358\u306a\u51e6\u7406\u306e\u5834\u5408\nnumbers = [1, 2, 3]\ndoubled = numbers.map { |n| n * 2 }<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-11\">2. do\u2026end\u3092\u4f7f\u3046\u65b9\u6cd5<\/h3>\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=\"\"># \u8907\u6570\u884c\u306e\u51e6\u7406\u304c\u5fc5\u8981\u306a\u5834\u5408\nusers = ['alice', 'bob']\nformatted_users = users.map do |user|\n  name = user.capitalize\n  age = rand(20..40)  # \u4f8b\u793a\u7528\u306e\u30e9\u30f3\u30c0\u30e0\u306a\u5e74\u9f62\n  \"#{name} (#{age}\u6b73)\"\nend<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-12\">\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3\u3092\u6d3b\u7528\u3059\u308b<\/li>\n<\/ol>\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=\"\"># \u826f\u3044\u4f8b\uff1a\u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3\u3067\u7c21\u6f54\u306b\u66f8\u304f\nnames = ['  alice  ', '  bob  ', '  carol  ']\ncleaned_names = names.map(&amp;:strip).map(&amp;:capitalize)\n\n# \u907f\u3051\u305f\u3044\u4f8b\uff1a\u4e2d\u9593\u5909\u6570\u3092\u4f7f\u3046\u5197\u9577\u306a\u66f8\u304d\u65b9\nnames = ['  alice  ', '  bob  ', '  carol  ']\ntrimmed = names.map { |n| n.strip }\ncleaned_names = trimmed.map { |n| n.capitalize }<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>\u30b7\u30f3\u30dc\u30eb\u3092\u4f7f\u3063\u305f\u7701\u7565\u8a18\u6cd5\u3092\u6d3b\u7528\u3059\u308b<\/li>\n<\/ol>\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=\"\"># \u30e1\u30bd\u30c3\u30c9\u3092\u5b9f\u884c\u3059\u308b\u3060\u3051\u306e\u5834\u5408\u306f&amp;:\u30e1\u30bd\u30c3\u30c9\u540d\u306e\u5f62\u5f0f\u304c\u4f7f\u3048\u308b\nnumbers = ['1', '2', '3']\nintegers = numbers.map(&amp;:to_i)  # \u6587\u5b57\u5217\u304b\u3089\u6574\u6570\u3078\u306e\u5909\u63db<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li>\u9069\u5207\u306a\u547d\u540d\u3067\u610f\u56f3\u3092\u660e\u78ba\u306b\u3059\u308b<\/li>\n<\/ol>\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=\"\"># \u826f\u3044\u4f8b\uff1a\u51e6\u7406\u306e\u610f\u56f3\u304c\u540d\u524d\u304b\u3089\u5206\u304b\u308b\nprices = [100, 200, 300]\nprices_with_tax = prices.map { |price| (price * 1.1).floor }\n\n# \u907f\u3051\u305f\u3044\u4f8b\uff1a\u51e6\u7406\u306e\u610f\u56f3\u304c\u5206\u304b\u308a\u306b\u304f\u3044\ndata = [100, 200, 300]\nresult = data.map { |x| (x * 1.1).floor }<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3092\u30de\u30b9\u30bf\u30fc\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u52b9\u7387\u7684\u3067\u53ef\u8aad\u6027\u306e\u9ad8\u3044\u30b3\u30fc\u30c9\u304c\u66f8\u3051\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3088\u308a\u9ad8\u5ea6\u306a\u5fdc\u7528\u30c6\u30af\u30cb\u30c3\u30af\u3092\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-13\">\u77e5\u3063\u3066\u304a\u304f\u3079\u304dmap\u306e\u5fdc\u7528\u30c6\u30af\u30cb\u30c3\u30af<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-14\">\u30cf\u30c3\u30b7\u30e5\u306b\u5bfe\u3059\u308bmap\u306e\u6d3b\u7528\u6cd5<\/h2>\n\n\n\n<p>\u30cf\u30c3\u30b7\u30e5\u306b\u5bfe\u3057\u3066<code>map<\/code>\u3092\u4f7f\u7528\u3059\u308b\u5834\u5408\u3001\u30d6\u30ed\u30c3\u30af\u5f15\u6570\u3068\u3057\u3066<code>key<\/code>\u3068<code>value<\/code>\u306e\u4e21\u65b9\u3092\u53d7\u3051\u53d6\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\uff1a<\/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=\"\"># \u30cf\u30c3\u30b7\u30e5\u306e\u5024\u3092\u5909\u63db\nuser_scores = { alice: 85, bob: 92, carol: 78 }\npassing_status = user_scores.map { |name, score| [name, score &gt;= 80] }.to_h\nputs passing_status  # \u51fa\u529b: {:alice=&gt;true, :bob=&gt;true, :carol=&gt;false}\n\n# \u30ad\u30fc\u3068\u5024\u306e\u4e21\u65b9\u3092\u52a0\u5de5\nprices = { apple: 100, banana: 200, orange: 150 }\nformatted_prices = prices.map { |item, price| \n  [\"\u5546\u54c1: #{item}\", \"#{price}\u5186\"]\n}.to_h\nputs formatted_prices\n# \u51fa\u529b: {\"\u5546\u54c1: apple\"=&gt;\"100\u5186\", \"\u5546\u54c1: banana\"=&gt;\"200\u5186\", \"\u5546\u54c1: orange\"=&gt;\"150\u5186\"}\n\n# \u30cd\u30b9\u30c8\u3057\u305f\u30cf\u30c3\u30b7\u30e5\u306e\u51e6\u7406\nusers = {\n  user1: { name: 'Alice', age: 25 },\n  user2: { name: 'Bob', age: 30 }\n}\nuser_summaries = users.map { |id, data| \n  [id, \"#{data[:name]}(#{data[:age]}\u6b73)\"]\n}.to_h\nputs user_summaries  # \u51fa\u529b: {:user1=&gt;\"Alice(25\u6b73)\", :user2=&gt;\"Bob(30\u6b73)\"}<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-15\">\u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3\u3067\u30b9\u30de\u30fc\u30c8\u306b\u66f8\u304f\u65b9\u6cd5<\/h2>\n\n\n\n<p>\u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3\u3092\u6d3b\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u8907\u6570\u306e\u51e6\u7406\u3092\u7c21\u6f54\u306b\u8a18\u8ff0\u3067\u304d\u307e\u3059\uff1a<\/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=\"\"># \u8907\u6570\u306e\u5909\u63db\u51e6\u7406\u3092\u9023\u7d50\nnumbers = [' 1 ', ' 2 ', ' 3 ']\nresult = numbers\n  .map(&amp;:strip)     # \u7a7a\u767d\u9664\u53bb\n  .map(&amp;:to_i)      # \u6574\u6570\u5909\u63db\n  .map { |n| n * 2} # 2\u500d\nputs result  # \u51fa\u529b: [2, 4, 6]\n\n# \u914d\u5217\u306e\u8981\u7d20\u3092\u52a0\u5de5\u3057\u3066\u6761\u4ef6\u3067\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\nusers = ['Alice', 'bob', ' Carol ', nil]\nvalid_users = users\n  .compact  # nil\u3092\u9664\u53bb\n  .map(&amp;:strip)  # \u7a7a\u767d\u9664\u53bb\n  .map(&amp;:capitalize)  # \u5148\u982d\u5927\u6587\u5b57\u5316\n  .select { |name| name.length &gt;= 4 }  # 4\u6587\u5b57\u4ee5\u4e0a\u3092\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\nputs valid_users  # \u51fa\u529b: [\"Alice\", \"Carol\"]\n\n# ActiveRecord\u30e9\u30a4\u30af\u306a\u51e6\u7406\u30c1\u30a7\u30fc\u30f3\nproducts = [\n  { name: 'Apple', price: 100 },\n  { name: 'Banana', price: 200 }\n]\nformatted_products = products\n  .map { |p| p.transform_keys(&amp;:to_s) }  # \u30b7\u30f3\u30dc\u30eb\u30ad\u30fc\u3092\u6587\u5b57\u5217\u306b\n  .map { |p| p.merge('tax' =&gt; p['price'] * 0.1) }  # \u7a0e\u984d\u8ffd\u52a0\nputs formatted_products\n# \u51fa\u529b: [{\"name\"=&gt;\"Apple\", \"price\"=&gt;100, \"tax\"=&gt;10.0}, ...]<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-16\">nil\u5bfe\u7b56\u3068map!\u306e\u4f7f\u3044\u5206\u3051<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-17\">nil\u5bfe\u7b56<\/h3>\n\n\n\n<p><code>nil<\/code>\u3092\u542b\u3080\u914d\u5217\u3092\u51e6\u7406\u3059\u308b\u969b\u306e\u5b89\u5168\u306a\u65b9\u6cd5\uff1a<\/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=\"\"># nil\u3092\u542b\u3080\u914d\u5217\u306e\u5b89\u5168\u306a\u51e6\u7406\ndata = ['1', nil, '3', '4']\n\n# \u65b9\u6cd51: compact\u3092\u4f7f\u7528\nresult1 = data.compact.map { |x| x.to_i }\nputs result1  # \u51fa\u529b: [1, 3, 4]\n\n# \u65b9\u6cd52: \u6761\u4ef6\u5206\u5c90\u3092\u4f7f\u7528\nresult2 = data.map { |x| x&amp;.to_i }\nputs result2  # \u51fa\u529b: [1, nil, 3, 4]\n\n# \u65b9\u6cd53: \u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u8a2d\u5b9a\nresult3 = data.map { |x| x ? x.to_i : 0 }\nputs result3  # \u51fa\u529b: [1, 0, 3, 4]<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-18\">map!\u306e\u7279\u5fb4\u3068\u4f7f\u3044\u5206\u3051<\/h3>\n\n\n\n<p><code>map!<\/code>\u306f\u7834\u58ca\u7684\u30e1\u30bd\u30c3\u30c9\u3067\u3001\u5143\u306e\u914d\u5217\u3092\u76f4\u63a5\u5909\u66f4\u3057\u307e\u3059\uff1a<\/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=\"\"># map!\u306e\u4f7f\u7528\u4f8b\nnumbers = [1, 2, 3]\nnumbers.map! { |n| n * 2 }\nputs numbers  # \u51fa\u529b: [2, 4, 6]\n\n# \u4f7f\u3044\u5206\u3051\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\ndef process_data(data)\n  # \u826f\u3044\u4f8b\uff1a\u65b0\u3057\u3044\u914d\u5217\u3092\u8fd4\u3059\n  data.map { |x| x * 2 }\nend\n\ndef update_data!(data)\n  # \u7834\u58ca\u7684\u30e1\u30bd\u30c3\u30c9\u306f!\u3092\u3064\u3051\u3066\u660e\u793a\n  data.map! { |x| x * 2 }\nend\n\n# \u4f7f\u7528\u4f8b\noriginal = [1, 2, 3]\nprocessed = process_data(original)\nputs \"Original: #{original}\"  # [1, 2, 3]\nputs \"Processed: #{processed}\"  # [2, 4, 6]\n\nupdate_data!(original)\nputs \"Updated: #{original}\"  # [2, 4, 6]<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u5fdc\u7528\u30c6\u30af\u30cb\u30c3\u30af\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u67d4\u8edf\u3067\u52b9\u7387\u7684\u306a\u30b3\u30fc\u30c9\u304c\u66f8\u3051\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u5b9f\u8df5\u7684\u306a\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-19\">\u5b9f\u8df5\u7684\u306a\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u3067\u5b66\u3076map\u6d3b\u7528\u8853<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-20\">API\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u30c7\u30fc\u30bf\u6574\u5f62\u30c6\u30af\u30cb\u30c3\u30af<\/h2>\n\n\n\n<p>\u5b9f\u52d9\u3067\u3088\u304f\u906d\u9047\u3059\u308bAPI\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u51e6\u7406\u4f8b\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\uff1a<\/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=\"\"># JSON\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u6574\u5f62\nrequire 'json'\n\n# API\u30ec\u30b9\u30dd\u30f3\u30b9\u3092\u60f3\u5b9a\u3057\u305fJSON\u30c7\u30fc\u30bf\napi_response = [\n  { \"id\" =&gt; 1, \"user_name\" =&gt; \"alice\", \"age\" =&gt; 25, \"active\" =&gt; true },\n  { \"id\" =&gt; 2, \"user_name\" =&gt; \"bob\", \"age\" =&gt; 30, \"active\" =&gt; false }\n]\n\n# \u5fc5\u8981\u306a\u30c7\u30fc\u30bf\u3060\u3051\u3092\u62bd\u51fa\u3057\u3066\u65b0\u3057\u3044\u5f62\u5f0f\u306b\u5909\u63db\nuser_summaries = api_response.map { |user|\n  {\n    name: user[\"user_name\"].capitalize,\n    status: user[\"active\"] ? \"\u30a2\u30af\u30c6\u30a3\u30d6\" : \"\u975e\u30a2\u30af\u30c6\u30a3\u30d6\",\n    age_group: user[\"age\"] &gt;= 30 ? \"30\u4ee3\u4ee5\u4e0a\" : \"20\u4ee3\"\n  }\n}\n\nputs user_summaries\n# \u51fa\u529b: [{:name=&gt;\"Alice\", :status=&gt;\"\u30a2\u30af\u30c6\u30a3\u30d6\", :age_group=&gt;\"20\u4ee3\"},\n#        {:name=&gt;\"Bob\", :status=&gt;\"\u975e\u30a2\u30af\u30c6\u30a3\u30d6\", :age_group=&gt;\"30\u4ee3\u4ee5\u4e0a\"}]\n\n# \u30cd\u30b9\u30c8\u3055\u308c\u305fAPI\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u51e6\u7406\nnested_response = {\n  \"data\" =&gt; {\n    \"users\" =&gt; [\n      { \"profile\" =&gt; { \"name\" =&gt; \"alice\", \"links\" =&gt; [\"twitter\", \"github\"] } },\n      { \"profile\" =&gt; { \"name\" =&gt; \"bob\", \"links\" =&gt; [\"facebook\"] } }\n    ]\n  }\n}\n\nuser_profiles = nested_response[\"data\"][\"users\"].map { |user|\n  name = user[\"profile\"][\"name\"]\n  links_count = user[\"profile\"][\"links\"].length\n  \"#{name.capitalize}(#{links_count}\u4ef6\u306e\u30ea\u30f3\u30af)\"\n}\n\nputs user_profiles  # \u51fa\u529b: [\"Alice(2\u4ef6\u306e\u30ea\u30f3\u30af)\", \"Bob(1\u4ef6\u306e\u30ea\u30f3\u30af)\"]<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-21\">\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u53d6\u5f97\u3057\u305f\u30ec\u30b3\u30fc\u30c9\u306e\u5909\u63db\u4f8b<\/h2>\n\n\n\n<p>ActiveRecord\u3092\u4f7f\u7528\u3057\u305f\u5834\u5408\u306e\u5b9f\u8df5\u7684\u306a\u4f8b\u3092\u898b\u3066\u307f\u307e\u3057\u3087\u3046\uff1a<\/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=\"\"># \u30e2\u30c7\u30eb\u306e\u5b9a\u7fa9\uff08\u4f8b\u793a\u7528\uff09\nclass User &lt; ApplicationRecord\n  has_many :orders\nend\n\nclass Order &lt; ApplicationRecord\n  belongs_to :user\nend\n\n# \u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30ec\u30b3\u30fc\u30c9\u306e\u5909\u63db\u4f8b\nusers_with_orders = User.includes(:orders).map { |user|\n  {\n    id: user.id,\n    name: user.name,\n    order_count: user.orders.count,\n    total_amount: user.orders.sum(&amp;:amount),\n    last_order_date: user.orders.maximum(:created_at)&amp;.strftime('%Y-%m-%d')\n  }\n}\n\n# \u95a2\u9023\u30c6\u30fc\u30d6\u30eb\u306e\u30c7\u30fc\u30bf\u3092\u542b\u3080\u8907\u96d1\u306a\u5909\u63db\ndetailed_orders = Order.includes(:user).map { |order|\n  {\n    order_id: order.id,\n    user_name: order.user.name,\n    amount: order.amount,\n    status: order.status,\n    created_date: order.created_at.strftime('%Y-%m-%d'),\n    summary: \"#{order.user.name}\u69d8\u306e\u6ce8\u6587(#{order.amount}\u5186)\"\n  }\n}<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-22\">CSV\u30c7\u30fc\u30bf\u51e6\u7406\u3067\u306e\u6d3b\u7528\u65b9\u6cd5<\/h2>\n\n\n\n<p>CSV\u30d5\u30a1\u30a4\u30eb\u306e\u8aad\u307f\u8fbc\u307f\u3068\u51e6\u7406\u306e\u5b9f\u8df5\u4f8b\uff1a<\/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 'csv'\n\n# CSV\u30c7\u30fc\u30bf\u306e\u8aad\u307f\u8fbc\u307f\u3068\u5909\u63db\ncsv_data = &lt;&lt;~CSV\nname,age,city\nAlice,25,Tokyo\nBob,30,Osaka\nCarol,28,Fukuoka\nCSV\n\n# CSV\u30c7\u30fc\u30bf\u3092\u69cb\u9020\u5316\u30c7\u30fc\u30bf\u306b\u5909\u63db\nusers = CSV.parse(csv_data, headers: true).map { |row|\n  {\n    name: row['name'],\n    age: row['age'].to_i,\n    city: row['city'],\n    adult: row['age'].to_i &gt;= 20\n  }\n}\n\nputs users\n# \u51fa\u529b: [{:name=&gt;\"Alice\", :age=&gt;25, :city=&gt;\"Tokyo\", :adult=&gt;true}, ...]\n\n# \u30c7\u30fc\u30bf\u306e\u96c6\u8a08\u3068\u5909\u63db\ncity_statistics = users.map { |user|\n  {\n    city: user[:city],\n    user_count: users.count { |u| u[:city] == user[:city] },\n    average_age: users\n      .select { |u| u[:city] == user[:city] }\n      .map { |u| u[:age] }\n      .sum.to_f \/ users.count { |u| u[:city] == user[:city] }\n  }\n}.uniq { |stat| stat[:city] }\n\n# CSV\u3078\u306e\u66f8\u304d\u51fa\u3057\u6e96\u5099\noutput_data = users.map { |user|\n  [\n    user[:name],\n    \"#{user[:age]}\u6b73\",\n    \"#{user[:city]}\u5728\u4f4f\",\n    user[:adult] ? \"\u6210\u4eba\" : \"\u672a\u6210\u4eba\"\n  ]\n}\n\n# \u65b0\u3057\u3044CSV\u306e\u4f5c\u6210\nCSV.open('processed_users.csv', 'w') do |csv|\n  csv &lt;&lt; ['\u6c0f\u540d', '\u5e74\u9f62', '\u5c45\u4f4f\u5730', '\u6210\u4eba\u533a\u5206']\n  output_data.each { |row| csv &lt;&lt; row }\nend<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u5b9f\u8df5\u7684\u306a\u4f8b\u3092\u901a\u3058\u3066\u3001<code>map<\/code>\u30e1\u30bd\u30c3\u30c9\u304c\u5b9f\u52d9\u3067\u3044\u304b\u306b\u6709\u7528\u304b\u304c\u308f\u304b\u308a\u307e\u3059\u3002\u7279\u306b\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>API\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u51e6\u7406\u3067\u306f\uff1a<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5fc5\u8981\u306a\u30c7\u30fc\u30bf\u306e\u62bd\u51fa\u3068\u5f62\u5f0f\u5909\u63db<\/li>\n\n\n\n<li>\u30cd\u30b9\u30c8\u3055\u308c\u305f\u30c7\u30fc\u30bf\u306e\u5e73\u5766\u5316<\/li>\n\n\n\n<li>\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u306e\u6574\u5f62<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u64cd\u4f5c\u3067\u306f\uff1a<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u95a2\u9023\u30c6\u30fc\u30d6\u30eb\u306e\u30c7\u30fc\u30bf\u7d50\u5408<\/li>\n\n\n\n<li>\u96c6\u8a08\u3068\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u5909\u63db<\/li>\n\n\n\n<li>\u8907\u6570\u30ec\u30b3\u30fc\u30c9\u306e\u4e00\u62ec\u51e6\u7406<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>CSV\u30c7\u30fc\u30bf\u51e6\u7406\u3067\u306f\uff1a<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u30c7\u30fc\u30bf\u306e\u8aad\u307f\u8fbc\u307f\u3068\u69cb\u9020\u5316<\/li>\n\n\n\n<li>\u7d71\u8a08\u60c5\u5831\u306e\u53ce\u96c6<\/li>\n\n\n\n<li>\u65b0\u3057\u3044\u5f62\u5f0f\u3067\u306e\u51fa\u529b<\/li>\n<\/ul>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u30d1\u30bf\u30fc\u30f3\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u51e6\u7406\u3082\u52b9\u7387\u7684\u306b\u5b9f\u88c5\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-23\">map\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u6700\u9069\u5316\u3059\u308b\u30b3\u30c4<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-24\">\u5927\u91cf\u30c7\u30fc\u30bf\u51e6\u7406\u6642\u306e\u6ce8\u610f\u70b9<\/h2>\n\n\n\n<p>\u5927\u91cf\u306e\u30c7\u30fc\u30bf\u3092\u51e6\u7406\u3059\u308b\u969b\u306f\u3001\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u6ce8\u610f\u3092\u6255\u3046\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\uff1a<\/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=\"\"># \u30e1\u30e2\u30ea\u3092\u5927\u91cf\u6d88\u8cbb\u3059\u308b\u4f8b\nlarge_array = (1..1_000_000).to_a\n# \u4e00\u5ea6\u306b\u3059\u3079\u3066\u306e\u8981\u7d20\u3092\u51e6\u7406\u3057\u3066\u65b0\u3057\u3044\u914d\u5217\u3092\u4f5c\u6210\nresult = large_array.map { |n| n * 2 }  # \u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u304c2\u500d\u306b\n\n# \u3088\u308a\u52b9\u7387\u7684\u306a\u51e6\u7406\u65b9\u6cd5\nrequire 'enumerator'\n\n# \u30d0\u30c3\u30c1\u51e6\u7406\u306b\u3088\u308b\u6700\u9069\u5316\nlarge_array.each_slice(1000).map do |batch|\n  batch.map { |n| n * 2 }\nend\n\n# Enumerator\u3092\u4f7f\u7528\u3057\u305f\u9045\u5ef6\u8a55\u4fa1\nlarge_array.lazy.map { |n| n * 2 }.take(100).force<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-25\">\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u6291\u3048\u308b\u30c6\u30af\u30cb\u30c3\u30af<\/h2>\n\n\n\n<p>\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u6291\u3048\u308b\u305f\u3081\u306e\u4e3b\u8981\u306a\u30c6\u30af\u30cb\u30c3\u30af\u3092\u7d39\u4ecb\u3057\u307e\u3059\uff1a<\/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=\"\"># 1. \u9045\u5ef6\u8a55\u4fa1\u3092\u6d3b\u7528\nnumbers = (1..Float::INFINITY)  # \u7121\u9650\u30b7\u30fc\u30b1\u30f3\u30b9\nresult = numbers\n  .lazy\n  .map { |n| n * 2 }\n  .select { |n| n % 4 == 0 }\n  .take(5)\n  .force\nputs result  # \u51fa\u529b: [4, 8, 12, 16, 20]\n\n# 2. \u30b9\u30c8\u30ea\u30fc\u30df\u30f3\u30b0\u51e6\u7406\nrequire 'csv'\n\n# \u5927\u304d\u306aCSV\u30d5\u30a1\u30a4\u30eb\u30921\u884c\u305a\u3064\u51e6\u7406\nCSV.foreach('large_file.csv').map do |row|\n  # \u5404\u884c\u3092\u51e6\u7406\n  process_row(row)\nend\n\n# 3. \u7834\u58ca\u7684\u30e1\u30bd\u30c3\u30c9\u306e\u9069\u5207\u306a\u4f7f\u7528\ndef process_large_data!(data)\n  # \u65b0\u3057\u3044\u914d\u5217\u3092\u4f5c\u6210\u305b\u305a\u306b\u65e2\u5b58\u306e\u914d\u5217\u3092\u66f4\u65b0\n  data.map! { |item| item * 2 }\nend<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-26\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u4e2d\u9593\u914d\u5217\u306e\u524a\u6e1b<\/li>\n<\/ol>\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=\"\"># \u907f\u3051\u308b\u3079\u304d\u4f8b\nresult = array\n  .map { |x| x + 1 }\n  .map { |x| x * 2 }\n  .map { |x| x.to_s }\n\n# \u6700\u9069\u5316\u4f8b\uff081\u56de\u306emap\u3067\u51e6\u7406\uff09\nresult = array.map { |x| ((x + 1) * 2).to_s }<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>\u9069\u5207\u306a\u30e1\u30bd\u30c3\u30c9\u306e\u9078\u629e<\/li>\n<\/ol>\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=\"\"># map\u304c\u4e0d\u8981\u306a\u5834\u5408\u306e\u4f8b\nnumbers = [1, 2, 3, 4, 5]\n\n# \u907f\u3051\u308b\u3079\u304d\u4f8b\uff08\u65b0\u3057\u3044\u914d\u5217\u304c\u4e0d\u8981\u306a\u5834\u5408\uff09\nnumbers.map { |n| puts n }\n\n# \u6700\u9069\u306a\u4f8b\nnumbers.each { |n| puts n }<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li>\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u30e2\u30cb\u30bf\u30ea\u30f3\u30b0<\/li>\n<\/ol>\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 'memory_profiler'\n\nreport = MemoryProfiler.report do\n  large_array.map { |n| heavy_processing(n) }\nend\n\nreport.pretty_print<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af\u3092\u9069\u5207\u306b\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u5927\u898f\u6a21\u306a\u30c7\u30fc\u30bf\u51e6\u7406\u3067\u3082\u30e1\u30e2\u30ea\u52b9\u7387\u306e\u826f\u3044\u5b9f\u88c5\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002\u7279\u306b\u91cd\u8981\u306a\u306e\u306f\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5fc5\u8981\u306a\u5206\u3060\u3051\u51e6\u7406\u3059\u308b\uff08\u9045\u5ef6\u8a55\u4fa1\uff09<\/li>\n\n\n\n<li>\u30d0\u30c3\u30c1\u51e6\u7406\u3092\u6d3b\u7528\u3059\u308b<\/li>\n\n\n\n<li>\u4e2d\u9593\u914d\u5217\u306e\u751f\u6210\u3092\u6700\u5c0f\u9650\u306b\u6291\u3048\u308b<\/li>\n\n\n\n<li>\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u5b9a\u671f\u7684\u306b\u30e2\u30cb\u30bf\u30ea\u30f3\u30b0\u3059\u308b<\/li>\n<\/ul>\n\n\n\n<p>\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3088\u304f\u3042\u308b\u9593\u9055\u3044\u3068\u305d\u306e\u89e3\u6c7a\u65b9\u6cd5\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-27\">\u3088\u304f\u3042\u308b\u9593\u9055\u3044\u3068\u89e3\u6c7a\u65b9\u6cd5<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-28\">\u7834\u58ca\u7684\u30e1\u30bd\u30c3\u30c9\u3067\u30cf\u30de\u308b\u30b1\u30fc\u30b9<\/h2>\n\n\n\n<p>\u7834\u58ca\u7684\u30e1\u30bd\u30c3\u30c9\u306e\u4f7f\u7528\u306f\u3001\u4e88\u671f\u305b\u306c\u30d0\u30b0\u306e\u539f\u56e0\u3068\u306a\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\uff1a<\/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=\"\"># \u4f8b1: \u5143\u30c7\u30fc\u30bf\u306e\u610f\u56f3\u3057\u306a\u3044\u5909\u66f4\ndef process_users(users)\n  # \u5371\u967a: \u5143\u306e\u914d\u5217\u304c\u5909\u66f4\u3055\u308c\u308b\n  users.map! { |user| user.upcase }\nend\n\nusers = ['alice', 'bob', 'carol']\nprocessed = process_users(users)\nputs users  # \u51fa\u529b: [\"ALICE\", \"BOB\", \"CAROL\"] - \u5143\u30c7\u30fc\u30bf\u304c\u5909\u66f4\u3055\u308c\u3066\u3044\u308b\uff01\n\n# \u89e3\u6c7a\u7b56: \u975e\u7834\u58ca\u7684\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\ndef safe_process_users(users)\n  users.map { |user| user.upcase }\nend\n\nusers = ['alice', 'bob', 'carol']\nprocessed = safe_process_users(users)\nputs users  # \u51fa\u529b: [\"alice\", \"bob\", \"carol\"] - \u5143\u30c7\u30fc\u30bf\u306f\u4fdd\u6301\u3055\u308c\u308b\nputs processed  # \u51fa\u529b: [\"ALICE\", \"BOB\", \"CAROL\"]<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-29\">\u30b9\u30b3\u30fc\u30d7\u306e\u52d8\u9055\u3044\u306b\u3088\u308b\u30d0\u30b0<\/h2>\n\n\n\n<p>\u30d6\u30ed\u30c3\u30af\u5185\u3067\u306e\u30b9\u30b3\u30fc\u30d7\u306e\u7406\u89e3\u4e0d\u8db3\u306b\u3088\u308b\u4e00\u822c\u7684\u306a\u9593\u9055\u3044\uff1a<\/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=\"\"># \u4f8b1: \u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u5909\u6570\u3078\u306e\u30a2\u30af\u30bb\u30b9\nclass UserProcessor\n  def initialize\n    @prefix = \"User: \"\n  end\n\n  def process_names(names)\n    # \u9593\u9055\u3044: \u30e9\u30e0\u30c0\u5f0f\u5185\u3067\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u5909\u6570\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u306a\u3044\n    names.map(&amp;:prefix_name)\n  end\n\n  # \u89e3\u6c7a\u7b561: \u901a\u5e38\u306e\u30d6\u30ed\u30c3\u30af\u3092\u4f7f\u7528\n  def correct_process_names(names)\n    names.map { |name| \"#{@prefix}#{name}\" }\n  end\n\n  # \u89e3\u6c7a\u7b562: \u30e1\u30bd\u30c3\u30c9\u3092\u5b9a\u7fa9\u3057\u3066\u53c2\u7167\n  def prefix_name(name)\n    \"#{@prefix}#{name}\"\n  end\n\n  def alternative_process_names(names)\n    names.map { |name| prefix_name(name) }\n  end\nend\n\n# \u4f8b2: \u5916\u90e8\u5909\u6570\u306e\u53c2\u7167\ndef format_items(items)\n  tax_rate = 0.1\n\n  # \u9593\u9055\u3044: \u30d6\u30ed\u30c3\u30af\u5185\u3067\u5b9a\u7fa9\u3057\u305f\u5909\u6570\u3092\u5916\u90e8\u3067\u4f7f\u7528\n  processed = items.map do |item|\n    price_with_tax = item * (1 + tax_rate)\n  end\n  # puts price_with_tax  # \u30a8\u30e9\u30fc: undefined local variable\n\n  # \u89e3\u6c7a\u7b56: \u5fc5\u8981\u306a\u5024\u3092\u623b\u308a\u5024\u3068\u3057\u3066\u8fd4\u3059\n  processed = items.map do |item|\n    item * (1 + tax_rate)\n  end\nend<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-30\">\u3088\u304f\u3042\u308b\u9593\u9055\u3044\u3068\u305d\u306e\u5bfe\u51e6\u6cd5<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li>nil\u306e\u6271\u3044\u306b\u95a2\u3059\u308b\u554f\u984c<\/li>\n<\/ol>\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=\"\"># \u9593\u9055\u3044: nil\u30c1\u30a7\u30c3\u30af\u306e\u4e0d\u8db3\ndata = [1, nil, 3, 4]\nresult = data.map { |x| x * 2 }  # NoMethodError: undefined method `*' for nil:NilClass\n\n# \u89e3\u6c7a\u7b561: nil\u306e\u4e8b\u524d\u9664\u53bb\nresult = data.compact.map { |x| x * 2 }\n\n# \u89e3\u6c7a\u7b562: \u6761\u4ef6\u5206\u5c90\u306b\u3088\u308b\u5bfe\u5fdc\nresult = data.map { |x| x ? x * 2 : 0 }\n\n# \u89e3\u6c7a\u7b563: \u307c\u3063\u3061\u6f14\u7b97\u5b50\u306e\u4f7f\u7528\nresult = data.map { |x| x&amp;.* 2 }<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>\u578b\u5909\u63db\u306e\u554f\u984c<\/li>\n<\/ol>\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=\"\"># \u9593\u9055\u3044: \u6697\u9ed9\u306e\u578b\u5909\u63db\u306b\u4f9d\u5b58\nnumbers = ['1', '2', '3']\nresult = numbers.map { |n| n + 1 }  # \"11\", \"21\", \"31\" \u3068\u306a\u308b\n\n# \u89e3\u6c7a\u7b56: \u660e\u793a\u7684\u306a\u578b\u5909\u63db\nresult = numbers.map { |n| n.to_i + 1 }<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u554f\u984c<\/li>\n<\/ol>\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=\"\"># \u9593\u9055\u3044: \u4e0d\u8981\u306a\u4e2d\u9593\u914d\u5217\u306e\u751f\u6210\nusers = ['alice', 'bob', 'carol']\nresult = users\n  .map { |u| u.strip }\n  .map { |u| u.capitalize }\n  .map { |u| u.reverse }\n\n# \u89e3\u6c7a\u7b56: \u51e6\u7406\u3092\u307e\u3068\u3081\u308b\nresult = users.map { |u| u.strip.capitalize.reverse }<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u554f\u984c\u3092\u56de\u907f\u3059\u308b\u305f\u3081\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30e1\u30bd\u30c3\u30c9\u306e\u547d\u540d\u898f\u5247\u3092\u5b88\u308b<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u7834\u58ca\u7684\u30e1\u30bd\u30c3\u30c9\u306b\u306f<code>!<\/code>\u3092\u3064\u3051\u308b<\/li>\n\n\n\n<li>\u623b\u308a\u5024\u306e\u578b\u304c\u5206\u304b\u308b\u540d\u524d\u3092\u4f7f\u7528<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u9069\u5207\u306a\u30a8\u30e9\u30fc\u30cf\u30f3\u30c9\u30ea\u30f3\u30b0<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>nil\u30c1\u30a7\u30c3\u30af\u3092\u5fd8\u308c\u306a\u3044<\/li>\n\n\n\n<li>\u578b\u5909\u63db\u306f\u660e\u793a\u7684\u306b\u884c\u3046<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30c6\u30b9\u30c8\u306e\u4f5c\u6210<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u306e\u30c6\u30b9\u30c8<\/li>\n\n\n\n<li>\u7834\u58ca\u7684\u30e1\u30bd\u30c3\u30c9\u306e\u52d5\u4f5c\u78ba\u8a8d<\/li>\n<\/ul>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u6ce8\u610f\u70b9\u3092\u610f\u8b58\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5b89\u5b9a\u3057\u305f\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-31\">\u4ee3\u66ff\u624b\u6bb5\u3068\u306e\u6bd4\u8f03\u3067\u308f\u304b\u308bmap\u306e\u4f7f\u3044\u3069\u3053\u308d<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-32\">collect\u3001map\u3001transform\u306e\u9055\u3044<\/h2>\n\n\n\n<p>Ruby\u306b\u306f\u914d\u5217\u3092\u5909\u63db\u3059\u308b\u8907\u6570\u306e\u30e1\u30bd\u30c3\u30c9\u304c\u7528\u610f\u3055\u308c\u3066\u3044\u307e\u3059\u3002\u305d\u308c\u305e\u308c\u306e\u7279\u5fb4\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\uff1a<\/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]\n\n# map \u3068 collect \u306f\u5b8c\u5168\u306b\u540c\u3058\nresult_map = numbers.map { |n| n * 2 }\nresult_collect = numbers.collect { |n| n * 2 }\nputs result_map == result_collect  # \u51fa\u529b: true\n\n# transform_values\u306f\u30cf\u30c3\u30b7\u30e5\u5c02\u7528\nhash = { a: 1, b: 2, c: 3 }\ntransformed = hash.transform_values { |v| v * 2 }\nputs transformed  # \u51fa\u529b: {:a=&gt;2, :b=&gt;4, :c=&gt;6}\n\n# \u4f7f\u3044\u5206\u3051\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\n# 1. \u914d\u5217\u306e\u5909\u63db\narray = [1, 2, 3]\ndoubled = array.map { |n| n * 2 }  # map\u3092\u4f7f\u7528\uff08\u4e00\u822c\u7684\uff09\n\n# 2. \u30cf\u30c3\u30b7\u30e5\u306e\u5024\u306e\u5909\u63db\nprices = { apple: 100, banana: 200 }\nwith_tax = prices.transform_values { |price| price * 1.1 }  # transform_values\u3092\u4f7f\u7528<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-33\">map\u3068inject\/reduce\u306e\u4f7f\u3044\u5206\u3051<\/h2>\n\n\n\n<p><code>map<\/code>\u3068<code>inject<\/code>\/<code>reduce<\/code>\u306f\u7570\u306a\u308b\u76ee\u7684\u3067\u4f7f\u7528\u3057\u307e\u3059\uff1a<\/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]\n\n# map\u306e\u5834\u5408\uff1a\u5404\u8981\u7d20\u3092\u5909\u63db\nsquares = numbers.map { |n| n ** 2 }\nputs squares  # \u51fa\u529b: [1, 4, 9, 16, 25]\n\n# inject\u306e\u5834\u5408\uff1a\u8981\u7d20\u3092\u96c6\u7d04\nsum = numbers.inject(0) { |result, n| result + n }\nputs sum  # \u51fa\u529b: 15\n\n# \u5b9f\u8df5\u7684\u306a\u4f7f\u3044\u5206\u3051\u4f8b\n\n# \u4f8b1: \u30e6\u30fc\u30b6\u30fc\u60c5\u5831\u306e\u6574\u5f62\uff08map\uff09\nusers = [\n  { name: 'Alice', age: 25 },\n  { name: 'Bob', age: 30 }\n]\n\n# map\u306e\u4f7f\u7528\u4f8b\uff1a\u5404\u30e6\u30fc\u30b6\u30fc\u306e\u60c5\u5831\u3092\u6574\u5f62\nformatted_users = users.map { |user| \n  \"#{user[:name]}(#{user[:age]}\u6b73)\"\n}\nputs formatted_users  # \u51fa\u529b: [\"Alice(25\u6b73)\", \"Bob(30\u6b73)\"]\n\n# \u4f8b2: \u5e74\u9f62\u306e\u96c6\u8a08\uff08inject\uff09\nage_summary = users.inject(Hash.new(0)) { |result, user|\n  result[user[:age] &gt;= 30 ? '30\u4ee3\u4ee5\u4e0a' : '20\u4ee3'] += 1\n  result\n}\nputs age_summary  # \u51fa\u529b: {\"20\u4ee3\"=&gt;1, \"30\u4ee3\u4ee5\u4e0a\"=&gt;1}\n\n# \u4e21\u8005\u3092\u7d44\u307f\u5408\u308f\u305b\u305f\u9ad8\u5ea6\u306a\u4f8b\norders = [\n  { product: 'Apple', quantity: 2, price: 100 },\n  { product: 'Banana', quantity: 3, price: 150 }\n]\n\n# \u6ce8\u6587\u60c5\u5831\u306e\u5909\u63db\u3068\u96c6\u8a08\norder_details = orders.map { |order|\n  # \u5404\u6ce8\u6587\u306e\u5c0f\u8a08\u3092\u8a08\u7b97\uff08map\uff09\n  subtotal = order[:quantity] * order[:price]\n  \"#{order[:product]}: #{subtotal}\u5186\"\n}.join(', ')  # \u6587\u5b57\u5217\u3068\u3057\u3066\u7d50\u5408\n\ntotal = orders.inject(0) { |sum, order|\n  # \u5408\u8a08\u91d1\u984d\u306e\u8a08\u7b97\uff08inject\uff09\n  sum + (order[:quantity] * order[:price])\n}\n\nputs \"\u6ce8\u6587\u5185\u5bb9: #{order_details}\"\nputs \"\u5408\u8a08: #{total}\u5186\"<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-34\">\u30e1\u30bd\u30c3\u30c9\u306e\u9078\u629e\u57fa\u6e96<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><code>map<\/code>\u3092\u4f7f\u3046\u3079\u304d\u5834\u5408\uff1a<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u914d\u5217\u306e\u5404\u8981\u7d20\u3092\u65b0\u3057\u3044\u5024\u306b\u5909\u63db\u3059\u308b<\/li>\n\n\n\n<li>\u7d50\u679c\u3068\u3057\u3066\u540c\u3058\u9577\u3055\u306e\u914d\u5217\u304c\u6b32\u3057\u3044<\/li>\n\n\n\n<li>\u5404\u8981\u7d20\u304c\u72ec\u7acb\u3057\u3066\u5909\u63db\u3067\u304d\u308b<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><code>inject<\/code>\/<code>reduce<\/code>\u3092\u4f7f\u3046\u3079\u304d\u5834\u5408\uff1a<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u914d\u5217\u306e\u8981\u7d20\u3092\u96c6\u7d04\u3057\u30661\u3064\u306e\u5024\u306b\u3059\u308b<\/li>\n\n\n\n<li>\u7d2f\u7a4d\u7684\u306a\u8a08\u7b97\u304c\u5fc5\u8981<\/li>\n\n\n\n<li>\u524d\u306e\u8a08\u7b97\u7d50\u679c\u3092\u6b21\u306e\u8a08\u7b97\u306b\u4f7f\u7528\u3059\u308b<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><code>transform_values<\/code>\u3092\u4f7f\u3046\u3079\u304d\u5834\u5408\uff1a<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u30cf\u30c3\u30b7\u30e5\u306e\u5024\u3060\u3051\u3092\u5909\u66f4\u3059\u308b<\/li>\n\n\n\n<li>\u30ad\u30fc\u306f\u305d\u306e\u307e\u307e\u4fdd\u6301\u3057\u305f\u3044<\/li>\n<\/ul>\n\n\n\n<p>\u9078\u629e\u306e\u30dd\u30a4\u30f3\u30c8\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u30c7\u30fc\u30bf\u69cb\u9020\uff1a\u914d\u5217\uff1f\u30cf\u30c3\u30b7\u30e5\uff1f<\/li>\n\n\n\n<li>\u671f\u5f85\u3059\u308b\u623b\u308a\u5024\u306e\u5f62\u5f0f<\/li>\n\n\n\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u8981\u4ef6<\/li>\n\n\n\n<li>\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027<\/li>\n<\/ul>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u9055\u3044\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u9069\u5207\u306a\u30e1\u30bd\u30c3\u30c9\u3092\u9078\u629e\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Ruby\u306emap\u30e1\u30bd\u30c3\u30c9\u3068\u306f\uff1f\u521d\u5fc3\u8005\u3067\u3082\u308f\u304b\u308b\u57fa\u790e\u77e5\u8b58 Warning: Undefined array key &#8220;is_admin&#8221; in \/home\/xs392991\/dexall.co.jp\/public_html &#8230; <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":{"0":"post-1336","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-ruby","7":"nothumb"},"_links":{"self":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/1336","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=1336"}],"version-history":[{"count":1,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/1336\/revisions"}],"predecessor-version":[{"id":1337,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/1336\/revisions\/1337"}],"wp:attachment":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1336"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1336"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1336"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}