{"id":30392,"date":"2023-01-14T19:11:07","date_gmt":"2023-01-14T13:41:07","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-memory-issues-in-memory-dataframe-best-approach-to-write-output\/"},"modified":"2023-01-14T19:11:07","modified_gmt":"2023-01-14T13:41:07","slug":"solved-memory-issues-in-memory-dataframe-best-approach-to-write-output","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-memory-issues-in-memory-dataframe-best-approach-to-write-output\/","title":{"rendered":"[Solved] Memory issues in-memory dataframe. Best approach to write output?"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-53097869\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"53097869\" data-parentid=\"52841760\" data-score=\"0\" 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 have been using the following snippet:<\/p>\n<pre><code>library(data.table)\nfilepaths &lt;- list.files(dir)\nresultFilename &lt;- \"\/path\/to\/resultFile.txt\"\nfor (i in 1:length(filepaths)) {\n  content &lt;- fread(filepaths, header = FALSE, sep = \",\")\n  ### some manipulation for the content \n  results &lt;- content[1]\n  fwrite(results, resultFilename, col.names = FALSE, quote = FALSE, append = TRUE)\n}\nfinalData &lt;- fread(resultFilename, header = FALSE, sep = \",\")\n<\/code><\/pre>\n<p>In my use case, for ~2000 files and tens of millions of rows the processing time decreased over 95 % compared with read.csv and incrementally increasing data into a data.frame in the loop. As you can see in <a rel=\"nofollow noopener\" target=\"_blank\" href=\"https:\/\/csgillespie.github.io\/efficientR\/importing-data.html\">https:\/\/csgillespie.github.io\/efficientR\/importing-data.html<\/a> section 4.3.1 and <a rel=\"nofollow noopener\" target=\"_blank\" href=\"https:\/\/www.r-bloggers.com\/fast-csv-writing-for-r\/\">https:\/\/www.r-bloggers.com\/fast-csv-writing-for-r\/<\/a>, <code>fread<\/code> and <code>fwrite<\/code> are very affordable data I\/O functions.<\/p>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">1<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved Memory issues in-memory dataframe. Best approach to write output? <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] I have been using the following snippet: library(data.table) filepaths &lt;- list.files(dir) resultFilename &lt;- &#8220;\/path\/to\/resultFile.txt&#8221; for (i in 1:length(filepaths)) { content &lt;- fread(filepaths, header = FALSE, sep = &#8220;,&#8221;) ### some manipulation for the content results &lt;- content[1] fwrite(results, resultFilename, col.names = FALSE, quote = FALSE, append = TRUE) } finalData &lt;- fread(resultFilename, header = &#8230; <a title=\"[Solved] Memory issues in-memory dataframe. Best approach to write output?\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-memory-issues-in-memory-dataframe-best-approach-to-write-output\/\" aria-label=\"More on [Solved] Memory issues in-memory dataframe. Best approach to write output?\">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":[1190,321,1154],"class_list":["post-30392","post","type-post","status-publish","format-standard","hentry","category-solved","tag-output","tag-r","tag-text-files"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] Memory issues in-memory dataframe. 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