{"id":12850,"date":"2022-10-02T03:48:55","date_gmt":"2022-10-01T22:18:55","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-trying-to-keep-the-same-type-after-saving-a-dataframe-in-a-csv-file\/"},"modified":"2022-10-02T03:48:55","modified_gmt":"2022-10-01T22:18:55","slug":"solved-trying-to-keep-the-same-type-after-saving-a-dataframe-in-a-csv-file","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-trying-to-keep-the-same-type-after-saving-a-dataframe-in-a-csv-file\/","title":{"rendered":"[Solved] Trying to keep the same type after saving a dataframe in a csv file"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-62129039\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"62129039\" data-parentid=\"62128730\" data-score=\"0\" data-position-on-page=\"2\" data-highest-scored=\"0\" data-question-has-accepted-highest-score=\"0\" itemprop=\"suggestedAnswer\" 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>csv files does not have a datatype definition header or something similar.<br \/>\nSo when your read a csv pandas tries to guess the types and this can change the datatypes.<br \/>\nYou have two possibile solutions:<\/p>\n<ol>\n<li>Provide the datatype list when you do read_csv with dtype and parse_dates keywords (<a rel=\"nofollow noopener\" target=\"_blank\" href=\"https:\/\/pandas.pydata.org\/pandas-docs\/stable\/reference\/api\/pandas.read_csv.html\">https:\/\/pandas.pydata.org\/pandas-docs\/stable\/reference\/api\/pandas.read_csv.html<\/a>)<\/li>\n<li>Use a different file format that store data with a schema (ex parquet)<\/li>\n<\/ol>\n<p>for example:<\/p>\n<pre><code>import pandas as pd\ndate = pd.to_datetime('01-01-2020')\n\ndf=pd.DataFrame({'col1':[1,2,3,4],'col2':['a','b','b','d'],'col3':[date,date,date,date]})\n\nprint('original \\n',df.dtypes)\n\ndf.to_csv('testtype.csv',index=False)\ndf_csv = pd.read_csv('testtype.csv')\nprint('simple csv read \\n',df_csv.dtypes)\n\ndf_csv = pd.read_csv('testtype.csv')\nprint('csv datatypes \\n',df_csv.dtypes)\n\ndf_csv = pd.read_csv('testtype.csv',parse_dates=[2])\nprint('csv with parse dates \\n',df_csv.dtypes)\n\ndf.to_parquet('testtype.pqt')\ndf_pqt=pd.read_parquet('testtype.pqt')\n\nprint('parquet  \\n',df_pqt.dtypes)\n<\/code><\/pre>\n<p>that output:<\/p>\n<pre><code>original \n col1             int64\ncol2            object\ncol3    datetime64[ns]\ndtype: object\n\nsimple csv read \n col1     int64\ncol2    object\ncol3    object\ndtype: object\n\ncsv datatypes \n col1     int64\ncol2    object\ncol3    object\ndtype: object\n\ncsv with parse dates \n col1             int64\ncol2            object\ncol3    datetime64[ns]\ndtype: object\n\nparquet  \n col1             int64\ncol2            object\ncol3    datetime64[ns]\ndtype: object\n<\/code><\/pre>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">2<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved Trying to keep the same type after saving a dataframe in a csv file <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] csv files does not have a datatype definition header or something similar. So when your read a csv pandas tries to guess the types and this can change the datatypes. You have two possibile solutions: Provide the datatype list when you do read_csv with dtype and parse_dates keywords (https:\/\/pandas.pydata.org\/pandas-docs\/stable\/reference\/api\/pandas.read_csv.html) Use a different file format &#8230; <a title=\"[Solved] Trying to keep the same type after saving a dataframe in a csv file\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-trying-to-keep-the-same-type-after-saving-a-dataframe-in-a-csv-file\/\" aria-label=\"More on [Solved] Trying to keep the same type after saving a dataframe in a csv file\">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":[461,349,482],"class_list":["post-12850","post","type-post","status-publish","format-standard","hentry","category-solved","tag-dataframe","tag-python","tag-python-3-x"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] Trying to keep the same type after saving a dataframe in a csv file - 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-trying-to-keep-the-same-type-after-saving-a-dataframe-in-a-csv-file\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Trying to keep the same type after saving a dataframe in a csv file - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] csv files does not have a datatype definition header or something similar. So when your read a csv pandas tries to guess the types and this can change the datatypes. You have two possibile solutions: Provide the datatype list when you do read_csv with dtype and parse_dates keywords (https:\/\/pandas.pydata.org\/pandas-docs\/stable\/reference\/api\/pandas.read_csv.html) Use a different file format ... Read more\" \/>\n<meta property=\"og:url\" content=\"https:\/\/jassweb.com\/solved\/solved-trying-to-keep-the-same-type-after-saving-a-dataframe-in-a-csv-file\/\" \/>\n<meta property=\"og:site_name\" content=\"JassWeb\" \/>\n<meta property=\"article:published_time\" content=\"2022-10-01T22:18:55+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=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-trying-to-keep-the-same-type-after-saving-a-dataframe-in-a-csv-file\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-trying-to-keep-the-same-type-after-saving-a-dataframe-in-a-csv-file\/\"},\"author\":{\"name\":\"Kirat\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31\"},\"headline\":\"[Solved] Trying to keep the same type after saving a dataframe in a csv file\",\"datePublished\":\"2022-10-01T22:18:55+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-trying-to-keep-the-same-type-after-saving-a-dataframe-in-a-csv-file\/\"},\"wordCount\":111,\"publisher\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\"},\"keywords\":[\"dataframe\",\"python\",\"python-3.x\"],\"articleSection\":[\"Solved\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-trying-to-keep-the-same-type-after-saving-a-dataframe-in-a-csv-file\/\",\"url\":\"https:\/\/jassweb.com\/solved\/solved-trying-to-keep-the-same-type-after-saving-a-dataframe-in-a-csv-file\/\",\"name\":\"[Solved] Trying to keep the same type after saving a dataframe in a csv file - 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So when your read a csv pandas tries to guess the types and this can change the datatypes. You have two possibile solutions: Provide the datatype list when you do read_csv with dtype and parse_dates keywords (https:\/\/pandas.pydata.org\/pandas-docs\/stable\/reference\/api\/pandas.read_csv.html) Use a different file format ... 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