{"id":5805,"date":"2022-08-30T16:10:29","date_gmt":"2022-08-30T10:40:29","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-how-to-sum-multiple-elements-of-nested-arrays-on-unique-keys-duplicate\/"},"modified":"2022-08-30T16:10:29","modified_gmt":"2022-08-30T10:40:29","slug":"solved-how-to-sum-multiple-elements-of-nested-arrays-on-unique-keys-duplicate","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-how-to-sum-multiple-elements-of-nested-arrays-on-unique-keys-duplicate\/","title":{"rendered":"[Solved] How to sum multiple elements of nested arrays on unique keys [duplicate]"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-37453063\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"37453063\" data-parentid=\"37452654\" data-score=\"1\" data-position-on-page=\"1\" data-highest-scored=\"1\" data-question-has-accepted-highest-score=\"1\" itemprop=\"acceptedAnswer\" itemscope itemtype=\"https:\/\/schema.org\/Answer\">\n<div class=\"post-layout\">\n<div class=\"votecell post-layout--left\"><\/div>\n<div class=\"answercell post-layout--right\">\n<div class=\"s-prose js-post-body\" itemprop=\"text\">\n<p>This is essentially the same as the solution to your previous question.<\/p>\n<pre><code>data = [ [ 123.0, 23, \"id1\", 34, \"abc\" ], \n         [ 234.1, 43, \"id2\", 24, \"jsk\" ],\n         [ 423.5, 53, \"id1\",  1, \"xyz\" ],\n         [   1.4,  5, \"id2\",  0, \"klm\" ] ]\n\nsums = Hash.new {|h,k| h[k] = [0, 0, 0] }\n\ndata.each_with_object(sums) do |(val0, val1, id, val2, _), sums|\n  sums[id][0] += val0\n  sums[id][1] += val1\n  sums[id][2] += val2\nend\n# =&gt; { \"id1\" =&gt; [ 546.5, 76, 35 ],\n#      \"id2\" =&gt; [ 235.5, 48, 24 ] }\n<\/code><\/pre>\n<p>The main difference is that instead of giving the Hash a default value of <code>0<\/code>, we&#8217;re giving it a default proc that initializes missing keys with <code>[0, 0, 0]<\/code>. (We can&#8217;t just do <code>Hash.new([0, 0, 0])<\/code> because then every value would be a reference to a single Array instance, rather than each value having its own Array.) Then, inside the block, we add each value (<code>val0<\/code> et al) to the corresponding elements of <code>sums[id]<\/code>.<\/p>\n<p>If you wanted an Array of Arrays instead of a Hash with the <code>id<\/code> at index 2, then at the end, you would have to add something like this:<\/p>\n<pre><code>.map {|id, vals| vals.insert(2, id) }\n<\/code><\/pre>\n<p>However, a Hash with the ids as keys makes more sense as a data structure.<\/p>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">3<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved How to sum multiple elements of nested arrays on unique keys [duplicate] <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] This is essentially the same as the solution to your previous question. data = [ [ 123.0, 23, &#8220;id1&#8221;, 34, &#8220;abc&#8221; ], [ 234.1, 43, &#8220;id2&#8221;, 24, &#8220;jsk&#8221; ], [ 423.5, 53, &#8220;id1&#8221;, 1, &#8220;xyz&#8221; ], [ 1.4, 5, &#8220;id2&#8221;, 0, &#8220;klm&#8221; ] ] sums = Hash.new {|h,k| h[k] = [0, 0, 0] } &#8230; <a title=\"[Solved] How to sum multiple elements of nested arrays on unique keys [duplicate]\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-how-to-sum-multiple-elements-of-nested-arrays-on-unique-keys-duplicate\/\" aria-label=\"More on [Solved] How to sum multiple elements of nested arrays on unique keys [duplicate]\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[361,455],"class_list":["post-5805","post","type-post","status-publish","format-standard","hentry","category-solved","tag-arrays","tag-ruby"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] How to sum multiple elements of nested arrays on unique keys [duplicate] - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-how-to-sum-multiple-elements-of-nested-arrays-on-unique-keys-duplicate\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] How to sum multiple elements of nested arrays on unique keys [duplicate] - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] This is essentially the same as the solution to your previous question. data = [ [ 123.0, 23, &quot;id1&quot;, 34, &quot;abc&quot; ], [ 234.1, 43, &quot;id2&quot;, 24, &quot;jsk&quot; ], [ 423.5, 53, &quot;id1&quot;, 1, &quot;xyz&quot; ], [ 1.4, 5, &quot;id2&quot;, 0, &quot;klm&quot; ] ] sums = Hash.new {|h,k| h[k] = [0, 0, 0] } ... 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