{"id":9915,"date":"2022-09-21T09:23:33","date_gmt":"2022-09-21T03:53:33","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-understanding-map-in-scala-closed\/"},"modified":"2022-09-21T09:23:33","modified_gmt":"2022-09-21T03:53:33","slug":"solved-understanding-map-in-scala-closed","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-understanding-map-in-scala-closed\/","title":{"rendered":"[Solved] Understanding map in Scala [closed]"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-44979011\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"44979011\" data-parentid=\"44978901\" 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><strong>1. <code>.map<\/code> in functional programming applies the function you want to each element of your collection.<\/strong><\/p>\n<p>Say, you want to add some data to each element in an array you have, which can be done as below, <\/p>\n<pre><code>scala&gt; val data = Array(\"a\", \"b\", \"c\")\ndata: Array[String] = Array(a, b, c)\n\nscala&gt; data.map(element =&gt; element+\"-add something\")\nres10: Array[String] = Array(a-add something, b-add something, c-add something)\n<\/code><\/pre>\n<p>Here, I&#8217;m saying, on each element <code>add something<\/code>, but <code>element<\/code> is unnecessary because you are adding on <code>every element<\/code> anyway. So, <code>_<\/code> is what represents <strong>any element<\/strong> here.<\/p>\n<p>So, same map can be done in following way.<\/p>\n<pre><code>scala&gt; data.map(_+\"-add something\")\nres9: Array[String] = Array(a-add something, b-add something, c-add something)\n<\/code><\/pre>\n<p>Also, note that <code>_<\/code> is used when you have one line mapping function.<\/p>\n<p><strong>2. <code>collection(index)<\/code> is the way to access nth element in a collection.<\/strong><\/p>\n<p>eg.<\/p>\n<pre><code>scala&gt; val collection = Array(Vector(1039), Vector(1010), Vector(1002), Vector(926))\ncollection: Array[scala.collection.immutable.Vector[Int]] = Array(Vector(1039), Vector(1010), Vector(1002), Vector(926))\n\nscala&gt; collection(0)\nres13: scala.collection.immutable.Vector[Int] = Vector(1039)\n<\/code><\/pre>\n<p>So, combining #1 and #2, in your case you are mapping the original collection and getting the first element.<\/p>\n<pre><code>scala&gt; collection.map(_.head)\nres17: Array[Int] = Array(1039, 1010, 1002, 926)\n<\/code><\/pre>\n<h2>Refs<\/h2>\n<p><a rel=\"nofollow noopener\" target=\"_blank\" href=\"https:\/\/twitter.github.io\/scala_school\/collections.html#map\">https:\/\/twitter.github.io\/scala_school\/collections.html#map<\/a><\/p>\n<p><a rel=\"nofollow noopener\" target=\"_blank\" href=\"http:\/\/www.brunton-spall.co.uk\/post\/2011\/12\/02\/map-map-and-flatmap-in-scala\/\">Map, Map and flatMap in Scala<\/a><\/p>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\"><\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved Understanding map in Scala [closed] <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] 1. .map in functional programming applies the function you want to each element of your collection. Say, you want to add some data to each element in an array you have, which can be done as below, scala&gt; val data = Array(&#8220;a&#8221;, &#8220;b&#8221;, &#8220;c&#8221;) data: Array[String] = Array(a, b, c) scala&gt; data.map(element =&gt; element+&#8221;-add &#8230; <a title=\"[Solved] Understanding map in Scala [closed]\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-understanding-map-in-scala-closed\/\" aria-label=\"More on [Solved] Understanding map in Scala [closed]\">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":[802],"class_list":["post-9915","post","type-post","status-publish","format-standard","hentry","category-solved","tag-scala"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] Understanding map in Scala [closed] - 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-understanding-map-in-scala-closed\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Understanding map in Scala [closed] - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] 1. .map in functional programming applies the function you want to each element of your collection. 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