{"id":18847,"date":"2022-11-02T03:54:36","date_gmt":"2022-11-01T22:24:36","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/"},"modified":"2022-11-02T03:54:36","modified_gmt":"2022-11-01T22:24:36","slug":"solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/","title":{"rendered":"[Solved] How to get quick summary in data.table with a look-back window?"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-44791145\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"44791145\" data-parentid=\"44688711\" 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>I think I understand your request. You seem to care about the order of the observations regardless if, for instance, the second observations <code>Time<\/code> is prior to the first observations <code>Time<\/code>. That doesn&#8217;t make much sense, but here is a quit efficient data.table solution in order to achieve this. This is basically does a <em>non-equi<\/em> join by <code>ID<\/code>, <code>Col<\/code>, Both <code>Time<\/code> columns <em>and<\/em> the row index (which is basically the appearance order). Afterwards, it just <code>dcast<\/code> to convert from long to wide (like in your previous question). Note that the result is ordered by the dates, but I&#8217;ve kept the <code>rowindx<\/code> variable, so you can reorder it back using <code>setorder<\/code>. Also, I&#8217;ll keep the ratio calc to you as this is very basic (hint &#8211; <em>Don&#8217;t<\/em> use loops, it is a fully vectorized one liner)<\/p>\n<pre><code>library(data.table) #v1.10.4+\n\n## Read the data\nDT &lt;- fread(\"ID   Time        Col   Count \nA    2017-06-05   M      1\nA    2017-06-02   M      1\nA    2017-06-03   M      1\nB    2017-06-02   K      1\nB    2017-06-01   M      4\")\n\n## Prepare the variables we need for the join\nDT[, Time := as.IDate(Time)]\nDT[, Time_2D := Time - 2L]\nDT[, rowindx := .I]\n\n## Non-equi join, sum `Count` by each join\nDT2 &lt;- DT[DT, \n          sum(Count), \n          on = .(ID, Col, rowindx &lt;= rowindx, Time &lt;= Time, Time &gt;= Time_2D),\n          by = .EACHI]\n\n## Fix column names (a known issue)\nsetnames(DT2, make.unique(names(DT2)))\n\n## Long to wide (You can reorder back using `rowindx` and `setorder` function)\ndcast(DT2, ID + Time + Time.1 + rowindx ~ Col, value.var = \"V1\", fill = 0)\n#    ID       Time     Time.1 rowindx K M\n# 1:  A 2017-06-02 2017-05-31       2 0 1\n# 2:  A 2017-06-03 2017-06-01       3 0 2\n# 3:  A 2017-06-05 2017-06-03       1 0 1\n# 4:  B 2017-06-01 2017-05-30       5 0 4\n# 5:  B 2017-06-02 2017-05-31       4 1 0\n<\/code><\/pre>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">4<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved How to get quick summary in data.table with a look-back window? <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] I think I understand your request. You seem to care about the order of the observations regardless if, for instance, the second observations Time is prior to the first observations Time. That doesn&#8217;t make much sense, but here is a quit efficient data.table solution in order to achieve this. This is basically does a &#8230; <a title=\"[Solved] How to get quick summary in data.table with a look-back window?\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/\" aria-label=\"More on [Solved] How to get quick summary in data.table with a look-back window?\">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":[1350,321],"class_list":["post-18847","post","type-post","status-publish","format-standard","hentry","category-solved","tag-data-table","tag-r"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] How to get quick summary in data.table with a look-back window? - 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-get-quick-summary-in-data-table-with-a-look-back-window\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] How to get quick summary in data.table with a look-back window? - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] I think I understand your request. You seem to care about the order of the observations regardless if, for instance, the second observations Time is prior to the first observations Time. That doesn&#8217;t make much sense, but here is a quit efficient data.table solution in order to achieve this. This is basically does a ... Read more\" \/>\n<meta property=\"og:url\" content=\"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/\" \/>\n<meta property=\"og:site_name\" content=\"JassWeb\" \/>\n<meta property=\"article:published_time\" content=\"2022-11-01T22:24:36+00:00\" \/>\n<meta name=\"author\" content=\"Kirat\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Kirat\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/\"},\"author\":{\"name\":\"Kirat\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31\"},\"headline\":\"[Solved] How to get quick summary in data.table with a look-back window?\",\"datePublished\":\"2022-11-01T22:24:36+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/\"},\"wordCount\":160,\"publisher\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\"},\"keywords\":[\"data.table\",\"r\"],\"articleSection\":[\"Solved\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/\",\"url\":\"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/\",\"name\":\"[Solved] How to get quick summary in data.table with a look-back window? - JassWeb\",\"isPartOf\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#website\"},\"datePublished\":\"2022-11-01T22:24:36+00:00\",\"breadcrumb\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/jassweb.com\/solved\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"[Solved] How to get quick summary in data.table with a look-back window?\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/jassweb.com\/solved\/#website\",\"url\":\"https:\/\/jassweb.com\/solved\/\",\"name\":\"JassWeb\",\"description\":\"Build High-quality Websites\",\"publisher\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/jassweb.com\/solved\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\",\"name\":\"Jass Web\",\"url\":\"https:\/\/jassweb.com\/solved\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png\",\"contentUrl\":\"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png\",\"width\":693,\"height\":132,\"caption\":\"Jass Web\"},\"image\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/\"}},{\"@type\":\"Person\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31\",\"name\":\"Kirat\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586\",\"contentUrl\":\"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586\",\"caption\":\"Kirat\"},\"sameAs\":[\"http:\/\/jassweb.com\"],\"url\":\"https:\/\/jassweb.com\/solved\/author\/jaspritsinghghumangmail-com\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"[Solved] How to get quick summary in data.table with a look-back window? - JassWeb","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/","og_locale":"en_US","og_type":"article","og_title":"[Solved] How to get quick summary in data.table with a look-back window? - JassWeb","og_description":"[ad_1] I think I understand your request. You seem to care about the order of the observations regardless if, for instance, the second observations Time is prior to the first observations Time. That doesn&#8217;t make much sense, but here is a quit efficient data.table solution in order to achieve this. This is basically does a ... Read more","og_url":"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/","og_site_name":"JassWeb","article_published_time":"2022-11-01T22:24:36+00:00","author":"Kirat","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Kirat","Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/#article","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/"},"author":{"name":"Kirat","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31"},"headline":"[Solved] How to get quick summary in data.table with a look-back window?","datePublished":"2022-11-01T22:24:36+00:00","mainEntityOfPage":{"@id":"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/"},"wordCount":160,"publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"keywords":["data.table","r"],"articleSection":["Solved"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/","url":"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/","name":"[Solved] How to get quick summary in data.table with a look-back window? - JassWeb","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/#website"},"datePublished":"2022-11-01T22:24:36+00:00","breadcrumb":{"@id":"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/jassweb.com\/solved\/solved-how-to-get-quick-summary-in-data-table-with-a-look-back-window\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/jassweb.com\/solved\/"},{"@type":"ListItem","position":2,"name":"[Solved] How to get quick summary in data.table with a look-back window?"}]},{"@type":"WebSite","@id":"https:\/\/jassweb.com\/solved\/#website","url":"https:\/\/jassweb.com\/solved\/","name":"JassWeb","description":"Build High-quality Websites","publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/jassweb.com\/solved\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/jassweb.com\/solved\/#organization","name":"Jass Web","url":"https:\/\/jassweb.com\/solved\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/","url":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","contentUrl":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","width":693,"height":132,"caption":"Jass Web"},"image":{"@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/"}},{"@type":"Person","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31","name":"Kirat","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/image\/","url":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586","contentUrl":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586","caption":"Kirat"},"sameAs":["http:\/\/jassweb.com"],"url":"https:\/\/jassweb.com\/solved\/author\/jaspritsinghghumangmail-com\/"}]}},"_links":{"self":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/18847","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/comments?post=18847"}],"version-history":[{"count":0,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/18847\/revisions"}],"wp:attachment":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/media?parent=18847"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/categories?post=18847"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/tags?post=18847"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}