{"id":4279,"date":"2022-08-22T04:32:05","date_gmt":"2022-08-21T23:02:05","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-how-to-convert-a-np-array-of-lists-to-a-np-array\/"},"modified":"2022-08-22T04:32:05","modified_gmt":"2022-08-21T23:02:05","slug":"solved-how-to-convert-a-np-array-of-lists-to-a-np-array","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-how-to-convert-a-np-array-of-lists-to-a-np-array\/","title":{"rendered":"[Solved] how to convert a np array of lists to a np array"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-49366760\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"49366760\" data-parentid=\"49364432\" 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 was wondering how you got the array of lists.  That usually takes some trickery.<\/p>\n<pre><code>In [2]: &gt;&gt;&gt; a = np.array([\"0,1\", \"2,3\", \"4,5\"])\n   ...: &gt;&gt;&gt; b = np.core.defchararray.split(a, sep=',')\n   ...: \nIn [4]: b\nOut[4]: array([list(['0', '1']), list(['2', '3']), list(['4', '5'])], dtype=object)\n<\/code><\/pre>\n<p>Simply calling array again doesn&#8217;t change things:<\/p>\n<pre><code>In [5]: np.array(b)\nOut[5]: array([list(['0', '1']), list(['2', '3']), list(['4', '5'])], dtype=object)\n<\/code><\/pre>\n<p><code>stack<\/code> works &#8211; it views <code>b<\/code> as a list of elements, in this case lists, and joins them on a new axis<\/p>\n<pre><code>In [6]: np.stack(b)\nOut[6]: \narray([['0', '1'],\n       ['2', '3'],\n       ['4', '5']], dtype=\"&lt;U1\")\nIn [7]: np.stack(b).astype(float)\nOut[7]: \narray([[0., 1.],\n       [2., 3.],\n       [4., 5.]])\n<\/code><\/pre>\n<p>But your &#8216;old&#8217; case was a 2d array of lists.  This stack trick does not work, at least not directly.<\/p>\n<pre><code>In [8]: a = np.array([\"0,1\", \"2,3\", \"4,5\",\"6,7\"]).reshape(2,2)\nIn [9]: b = np.core.defchararray.split(a, sep=',')\nIn [11]: np.stack(b)\nOut[11]: \narray([[list(['0', '1']), list(['2', '3'])],\n       [list(['4', '5']), list(['6', '7'])]], dtype=object)\n\nIn [12]: np.stack(b.ravel())\nOut[12]: \narray([['0', '1'],\n       ['2', '3'],\n       ['4', '5'],\n       ['6', '7']], dtype=\"&lt;U1\")\n<\/code><\/pre>\n<p>or<\/p>\n<pre><code>In [13]: np.array(b.tolist())\nOut[13]: \narray([[['0', '1'],\n        ['2', '3']],\n\n       [['4', '5'],\n        ['6', '7']]], dtype=\"&lt;U1\")\n<\/code><\/pre>\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 how to convert a np array of lists to a np array <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] I was wondering how you got the array of lists. That usually takes some trickery. In [2]: &gt;&gt;&gt; a = np.array([&#8220;0,1&#8221;, &#8220;2,3&#8221;, &#8220;4,5&#8221;]) &#8230;: &gt;&gt;&gt; b = np.core.defchararray.split(a, sep=&#8217;,&#8217;) &#8230;: In [4]: b Out[4]: array([list([&#8216;0&#8217;, &#8216;1&#8217;]), list([&#8216;2&#8217;, &#8216;3&#8217;]), list([&#8216;4&#8217;, &#8216;5&#8217;])], dtype=object) Simply calling array again doesn&#8217;t change things: In [5]: np.array(b) Out[5]: array([list([&#8216;0&#8217;, &#8216;1&#8217;]), &#8230; <a title=\"[Solved] how to convert a np array of lists to a np array\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-how-to-convert-a-np-array-of-lists-to-a-np-array\/\" aria-label=\"More on [Solved] how to convert a np array of lists to a np 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":[581,349],"class_list":["post-4279","post","type-post","status-publish","format-standard","hentry","category-solved","tag-numpy","tag-python"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] how to convert a np array of lists to a np 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-how-to-convert-a-np-array-of-lists-to-a-np-array\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] how to convert a np array of lists to a np array - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] I was wondering how you got the array of lists. That usually takes some trickery. In [2]: &gt;&gt;&gt; a = np.array([&quot;0,1&quot;, &quot;2,3&quot;, &quot;4,5&quot;]) ...: &gt;&gt;&gt; b = np.core.defchararray.split(a, sep=&#039;,&#039;) ...: In [4]: b Out[4]: array([list([&#039;0&#039;, &#039;1&#039;]), list([&#039;2&#039;, &#039;3&#039;]), list([&#039;4&#039;, &#039;5&#039;])], dtype=object) Simply calling array again doesn&#8217;t change things: In [5]: np.array(b) Out[5]: array([list([&#039;0&#039;, &#039;1&#039;]), ... 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