{"id":16507,"date":"2022-10-19T09:09:39","date_gmt":"2022-10-19T03:39:39","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-javascript-sorting-and-grouping-items-in-array\/"},"modified":"2022-10-19T09:09:39","modified_gmt":"2022-10-19T03:39:39","slug":"solved-javascript-sorting-and-grouping-items-in-array","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-javascript-sorting-and-grouping-items-in-array\/","title":{"rendered":"[Solved] JavaScript sorting and grouping items in array"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-45410403\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"45410403\" data-parentid=\"45410237\" data-score=\"2\" 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>Use objects for the grouping.<\/p>\n<pre><code>var categories = {};\n\nfunction incrementBy(category, value) {\n  if (!categories[category]) {\n    categories[category] = 0;\n  }\n  categories[category] += value;\n}\n\nvar datasetarr = [];\nvar pos;\nfor(var i = 0; i &lt; arr.length; i++){\n  console.log('unsorted ' + arr[i].type + ' ' + arr[i].quantity);\n  incrementBy(arr[i].type, arr[i].quantity)\n}\n\nfor(var category in categories){\n  console.log('sorted ' + category + ' ' + categories[category]);\n}\n<\/code><\/pre>\n<p>You can decompose the object if needed, through it into an array and sort it if required.<\/p>\n<p>A little bit cleaner example, which might let you follow along a little bite better:<\/p>\n<pre><code>var arr = [{type: 'kitchen appliance', quantity: 2},\n    {type: 'home entertainment', quantity: 2},\n    {type: 'home entertainment', quantity: 3},\n    {type: 'batteries &amp; lightings', quantity: 2},\n    {type: 'home entertainment', quantity: 2},\n    {type: 'home appliance', quantity: 5},\n    {type: 'kitchen appliance', quantity: 4},\n    {type: 'kitchen appliance', quantity: 5},\n    {type: 'kitchen appliance', quantity: 3},\n    {type: 'kitchen appliance', quantity: 4},\n    {type: 'kitchen appliance', quantity: 1},\n    {type: 'home entertainment', quantity: 1},\n    {type: 'home appliance', quantity: 5},\n    {type: 'batteries &amp; lightings', quantity: 2},\n    {type: 'kitchen appliance', quantity: 2},\n    {type: 'home appliance', quantity: 2}];\n\n\nfunction group(array) {\n    var categories = {};\n\n    function incrementBy(category, value) {\n        if (!categories[category]) {\n            categories[category] = 0;\n        }\n        categories[category] += value;\n    }\n\n    array.forEach(function (value, index, arr) {\n        incrementBy(value.type, value.quantity)\n    });\n\n    return categories;\n}\n\nfunction print(categories) {\n    for (var category in categories) {\n        console.log('%s: %s', category, categories[category]);\n    }\n}\n\nprint(group(arr));\n<\/code><\/pre>\n<p>Here a solution of of <code>group<\/code> hiding the grouping, which than can hold your own implementation:<\/p>\n<pre><code>function group(array) {\n    var categories = {};\n\n    function incrementBy(object) {\n        var category = categories[object.type];\n        if (!category) {\n            category = categories[object.type] = {};\n        }\n        var subCategory = category[object.subType];\n        if (!subCategory) {\n            subCategory = category[object.subType] = {};\n        }\n        subCategory += object.value;\n    }\n\n    array.forEach(function (value, index, arr) {\n        incrementBy(value, value.quantity)\n    });\n\n    return categories;\n}\n<\/code><\/pre>\n<p>Depending on your use case, you could also flatten the structure:<\/p>\n<pre><code>function incrementBy(object) {\n    var key = [object.type, object.subType].join(\"https:\/\/stackoverflow.com\/\");\n    var category = categories[key];\n    if (!category) {\n        category = categories[key] = {};\n    }\n    subCategory += object.value;\n}\n<\/code><\/pre>\n<p>But it might make sense to have various maps in place:<\/p>\n<pre><code>function groupings(array) {\n    var groupings = {\n      types: {},\n      subTypes: {},\n      paths: {}\n    };\n\n    function incrementBy(object) {\n        var category = groupings['types'][object.type];\n        if (!category) {\n            category = groupings['types'][object.type] = {};\n        }\n        category += object.value;\n\n        var subCategory = groupings['subTypes'][object.subType];\n        if (!subCategory) {\n            subCategory = groupings['subTypes'][object.subType] = {};\n        }\n        subCategory += object.value;\n\n\n        var key = [object.type, object.subType].join(\"https:\/\/stackoverflow.com\/\");\n        var path = groupings['paths'][key];\n        if (!path) {\n            path = groupings['paths'][key] = {};\n        }\n        path += object.value;\n    }\n\n    array.forEach(function (value, index, arr) {\n        incrementBy(value, value.quantity)\n    });\n\n    return categories;\n}\n<\/code><\/pre>\n<p>To avoid information loss on aggregations, you could simply create a more complex data structure:<\/p>\n<pre><code>function groupByAndSumBy(data, groupByProperty, sumByProperty) {\n  var accumulator = {};\n\n  data.forEach(function(object, index, array) {\n      var localAcc = accumulator[groupByProperty]\n            = accumulator[groupByProperty] || { items: [] };\n      localAcc[sumByProperty]\n            = (localAcc[sumByProperty] || 0) + object[sumByProperty];\n      localAcc.items.push(object);\n  });\n\n  return accumulator;\n}\n\nfunction groupByMerchantNameAndSumByTotalSales(data) {\n    return groupByAndSumBy(data, 'merchantName', 'totalSales');\n}\n<\/code><\/pre>\n<p>This creates an aggregation which also contains the subset of the input array, which allows you a more detailed view on the data.<\/p>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">8<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved JavaScript sorting and grouping items in array <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] Use objects for the grouping. var categories = {}; function incrementBy(category, value) { if (!categories[category]) { categories[category] = 0; } categories[category] += value; } var datasetarr = []; var pos; for(var i = 0; i &lt; arr.length; i++){ console.log(&#8216;unsorted &#8216; + arr[i].type + &#8216; &#8216; + arr[i].quantity); incrementBy(arr[i].type, arr[i].quantity) } for(var category in categories){ &#8230; <a title=\"[Solved] JavaScript sorting and grouping items in array\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-javascript-sorting-and-grouping-items-in-array\/\" aria-label=\"More on [Solved] JavaScript sorting and grouping items in array\">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":[361,1047,333,561],"class_list":["post-16507","post","type-post","status-publish","format-standard","hentry","category-solved","tag-arrays","tag-grouping","tag-javascript","tag-sorting"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] JavaScript sorting and grouping items in array - 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-javascript-sorting-and-grouping-items-in-array\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] JavaScript sorting and grouping items in array - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] Use objects for the grouping. var categories = {}; function incrementBy(category, value) { if (!categories[category]) { categories[category] = 0; } categories[category] += value; } var datasetarr = []; var pos; for(var i = 0; i &lt; arr.length; i++){ console.log(&#039;unsorted &#039; + arr[i].type + &#039; &#039; + arr[i].quantity); incrementBy(arr[i].type, arr[i].quantity) } for(var category in categories){ ... 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