{"id":9556,"date":"2021-06-13T18:24:27","date_gmt":"2021-06-13T12:54:27","guid":{"rendered":"https:\/\/pynative.com\/?p=9556"},"modified":"2021-07-03T12:08:58","modified_gmt":"2021-07-03T06:38:58","slug":"python-read-specific-lines-from-a-file","status":"publish","type":"post","link":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/","title":{"rendered":"Read Specific Lines From a File in Python"},"content":{"rendered":"\n<p>This article lets you know how to read a specific lines from a file by line number in Python.<\/p>\n\n\n\n<div class=\"wp-block-yoast-seo-table-of-contents yoast-table-of-contents\"><h2>Table of contents<\/h2><ul><li><a href=\"#h-steps-to-read-specific-lines-from-a-file\" data-level=\"2\">Steps To Read Specific Lines From A File<\/a><ul><li><a href=\"#h-example-read-specific-lines-from-file-by-line-number\" data-level=\"3\">Example: Read specific lines from file by line number<\/a><\/li><\/ul><\/li><li><a href=\"#h-linecache-module-read-line-from-a-file-by-line-number\" data-level=\"2\">linecache Module Read line from a file by line number<\/a><\/li><li><a href=\"#h-use-readlines-to-read-the-range-of-line-from-the-file\" data-level=\"2\">Use readlines() to Read the range of line from the File<\/a><\/li><li><a href=\"#h-generator-to-read-lines-from-a-file-by-line-number\" data-level=\"2\">Generator to Read Lines from a file by line number<\/a><\/li><li><a href=\"#h-for-loop-in-fileobject-to-read-specific-lines-in-python\" data-level=\"2\">for Loop in fileobject to Read Specific Lines in Python<\/a><\/li><li><a href=\"#h-conclusion\" data-level=\"2\">Conclusion<\/a><\/li><\/ul><\/div>\n\n\n\n<h2 class=\"stepsh wp-block-heading\" id=\"h-steps-to-read-specific-lines-from-a-file\">Steps To Read Specific Lines From A File<\/h2>\n\n\n\n<div class=\"wp-block-columns steps is-layout-flex wp-container-core-columns-is-layout-1 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"schema-how-to wp-block-yoast-how-to-block\"><p class=\"schema-how-to-description\">Let&#8217;s assume the file to read is significantly large (in GB), and you don&#8217;t want to read the whole file in memory at once but only want to jump and read lines #5 and #120. To read specific lines from a text file, Please follow these steps:<\/p> <ol class=\"schema-how-to-steps\"><li class=\"schema-how-to-step\" id=\"how-to-step-1623072196137\"><strong class=\"schema-how-to-step-name\">Open file in Read Mode<\/strong> <p class=\"schema-how-to-step-text\">To <a href=\"https:\/\/pynative.com\/python-file-open\/\">open a file<\/a> pass file path and access mode <code>r<\/code> to the <code>open()<\/code> function. The access mode specifies the operation you wanted to perform on the file, such as reading or writing.<br\/>For example, <code>fp= open(r'File_Path', 'r')<\/code> to <a href=\"https:\/\/pynative.com\/python-read-file\/\">read a file<\/a>.<\/p> <\/li><li class=\"schema-how-to-step\" id=\"how-to-step-1623726533105\"><strong class=\"schema-how-to-step-name\">Create a list to store line numbers<\/strong> <p class=\"schema-how-to-step-text\">Create a <a href=\"https:\/\/pynative.com\/python-lists\/\">list<\/a> with the number of each line in a text file to read. <br\/>For example, <code>line_numbers = [4, 7]<\/code>. Here we are reading lines 4 and 7.<\/p> <\/li><li class=\"schema-how-to-step\" id=\"how-to-step-1623142924301\"><strong class=\"schema-how-to-step-name\">Create a list to store lines<\/strong> <p class=\"schema-how-to-step-text\">After reading line 4 and 7 we will store result it in a list variable.<\/p> <\/li><li class=\"schema-how-to-step\" id=\"how-to-step-1623072253286\"><strong class=\"schema-how-to-step-name\">Use for loop with enumerate() function to get a line and its number.<\/strong> <p class=\"schema-how-to-step-text\">The <a href=\"https:\/\/docs.python.org\/3\/library\/functions.html#enumerate\">enumerate()<\/a> function adds a counter to an iterable and returns it in enumerate object. Pass the file pointer returned by the <code>open()<\/code> function to the <code>enumerate()<\/code>. <br\/>We can use this enumerate object with a <a href=\"https:\/\/pynative.com\/python-for-loop\/\">for loop<\/a> to access the line number.<br\/><strong>Note<\/strong>: <code>enumerate(file_pointer)<\/code> doesn&#8217;t load the entire file in memory, so this is an efficient solution.<\/p> <\/li><li class=\"schema-how-to-step\" id=\"how-to-step-1623142058359\"><strong class=\"schema-how-to-step-name\">Read file by line number<\/strong> <p class=\"schema-how-to-step-text\">Use the if condition in each iteration of a loop to check the line number. If it matches, then save that line into a list.<\/p> <\/li><\/ol><\/div>\n<\/div>\n<\/div>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"h-example-read-specific-lines-from-file-by-line-number\">Example: Read specific lines from file by line number<\/h3>\n\n\n\n<p>The following code shows&nbsp;<strong>how to read a text file by line number <\/strong>in Python.  See the attached file used in the example and an image to show the file\u2019s content for reference.<\/p>\n\n\n\n<p>In this example, we are <strong>reading line number 4 and 7<\/strong> and storing it in a list variable.<\/p>\n\n\n\n<div class=\"wp-block-image is-style-default\"><figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"450\" height=\"257\" src=\"https:\/\/pynative.com\/wp-content\/uploads\/2021\/06\/sample_text_file-1.png\" alt=\"text file\" class=\"wp-image-9615\" srcset=\"https:\/\/pynative.com\/wp-content\/uploads\/2021\/06\/sample_text_file-1.png 450w, https:\/\/pynative.com\/wp-content\/uploads\/2021\/06\/sample_text_file-1-300x171.png 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption>text file<\/figcaption><\/figure><\/div>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code1\"  id=\"norun\" class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-1\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">with<\/span> open(<span class=\"hljs-string\">r\"E:\\demos\\files\\read_demo.txt\"<\/span>, <span class=\"hljs-string\">'r'<\/span>) <span class=\"hljs-keyword\">as<\/span> fp:\n    <span class=\"hljs-comment\"># lines to read<\/span>\n    line_numbers = &#91;<span class=\"hljs-number\">4<\/span>, <span class=\"hljs-number\">7<\/span>]\n    <span class=\"hljs-comment\"># To store lines<\/span>\n    lines = &#91;]\n    <span class=\"hljs-keyword\">for<\/span> i, line <span class=\"hljs-keyword\">in<\/span> enumerate(fp):\n        <span class=\"hljs-comment\"># read line 4 and 7<\/span>\n        <span class=\"hljs-keyword\">if<\/span> i <span class=\"hljs-keyword\">in<\/span> line_numbers:\n            lines.append(line.strip())\n        <span class=\"hljs-keyword\">elif<\/span> i &gt; <span class=\"hljs-number\">7<\/span>:\n            <span class=\"hljs-comment\"># don't read after line 7 to save time<\/span>\n            <span class=\"hljs-keyword\">break<\/span>\nprint(lines)\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-1\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code1', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><\/div>\n\n\n<p><strong>Output<\/strong>:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">['Fifth line', 'Eighth Line']<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-linecache-module-read-line-from-a-file-by-line-number\">linecache Module Read line from a file by line number<\/h2>\n\n\n\n<p>In this section, we&#8217;ll see how to read file by line number using a linecache module.<\/p>\n\n\n\n<p>Python&#8217;s linecache is another performance-optimized way to <strong>jump to a particular line<\/strong> in a text file. Assume if you have a large text file, then linecache is the correct choice.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>The <a href=\"https:\/\/docs.python.org\/3\/library\/linecache.html\" target=\"_blank\" rel=\"noreferrer noopener\">linecache<\/a> module allows one to get any line from a Python source file, while attempting to optimize internally, using a cache, the common case where many lines are read from a single file. This is used by the traceback module to retrieve source lines for inclusion in the formatted traceback.<\/p><cite>Python Documentation<\/cite><\/blockquote>\n\n\n\n<p><strong>Use <\/strong>the <code>linecache.getline()<\/code> method to read specific line from a file.<\/p>\n\n\n<pre id=\"syntax\" class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-2\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">linecache.getline(filename, lineno, module_globals=<span class=\"hljs-literal\">None<\/span>)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-2\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<ul><li>Get line <code>lineno<\/code> from a file named <code>filename<\/code>. This function will not return any error if the line is not present in a file instead, it will return an empty string.<\/li><li>Change the <code>lineno<\/code> to your desired line number, and you&#8217;re ready to go.<\/li><\/ul>\n\n\n\n<p><strong>Example<\/strong><\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code2\"  id=\"norun\" class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-3\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> linecache\n\n<span class=\"hljs-comment\"># read fifth line<\/span>\nline = linecache.getline(<span class=\"hljs-string\">r\"E:\\demos\\files\\read_demo.txt\"<\/span>, <span class=\"hljs-number\">5<\/span>)\nprint(line)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-3\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code2', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><\/div>\n\n\n<p><strong>Output<\/strong>:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">Fifth line<\/pre>\n\n\n\n<p class=\"has-background\" style=\"background-color:#fbefd5\"><strong>Note<\/strong>: The linache reads the whole file in memory. So, if random access to line number is more important than performance, then use linache.<\/p>\n\n\n\n<p>If you want to read more than one line number from a file using linecache use the below example.<\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code3\"  id=\"norun\" class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-4\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> linecache\n\nline_numbers = &#91;<span class=\"hljs-number\">2<\/span>, <span class=\"hljs-number\">4<\/span>]\nlines = &#91;]\n<span class=\"hljs-keyword\">for<\/span> i <span class=\"hljs-keyword\">in<\/span> line_numbers:\n    x = linecache.getline(<span class=\"hljs-string\">r\"E:\\demos\\files\\read_demo.txt\"<\/span>, i).strip()\n    lines.append(x)\nprint(lines)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-4\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code3', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><\/div>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-use-readlines-to-read-the-range-of-line-from-the-file\">Use <code>readlines()<\/code> to Read the range of line from the File<\/h2>\n\n\n\n<p>If your file size is small and you are not concerned with performance, then the <a href=\"https:\/\/pynative.com\/python-read-file\/#h-readlines-reading-file-into-list\">readlines()<\/a> method is best suited.<\/p>\n\n\n\n<p>Reading a file in Python is fast if the file size is in a few MB. <\/p>\n\n\n\n<p>The <strong><code>readlines()<\/code> method reads all lines from a file<\/strong> and stores it in a list. You can use an index number as a line number to extract a set of lines from it. <\/p>\n\n\n\n<p>This is the most straightforward way to read a specific line from a file in Python. We read the entire file using this way and then pick specific lines from it as per our requirement.<\/p>\n\n\n\n<p>Use <code>readlines()[start:end]<\/code> to read range of lines.<\/p>\n\n\n\n<ul><li>the start is the starting line number<\/li><li>the end is the last line number<\/li><li>To read from line number 3 to 5 use <code>readlines()[2:5]<\/code><\/li><li>To read a single line use <code>fp.readlines()[2]<\/code>. this will read the third line.<\/li><\/ul>\n\n\n\n<p><strong>Example<\/strong>: Read line from 3 to 5<\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code4\"  id=\"norun\" class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-5\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">with<\/span> open(<span class=\"hljs-string\">r\"E:\\demos\\files\\read_demo.txt\"<\/span>, <span class=\"hljs-string\">'r'<\/span>) <span class=\"hljs-keyword\">as<\/span> fp:\n    <span class=\"hljs-comment\"># read line number 3 to 5<\/span>\n    <span class=\"hljs-comment\"># index starts from 0<\/span>\n    x = fp.readlines()&#91;<span class=\"hljs-number\">2<\/span>:<span class=\"hljs-number\">5<\/span>]\n    print(x)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-5\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code4', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><\/div>\n\n\n<p><strong>Example<\/strong>: Read line 8<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-6\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">with<\/span> open(<span class=\"hljs-string\">r\"E:\\demos\\files\\read_demo.txt\"<\/span>, <span class=\"hljs-string\">'r'<\/span>) <span class=\"hljs-keyword\">as<\/span> fp:\n    <span class=\"hljs-comment\"># read line 8<\/span>\n    x = fp.readlines()&#91;<span class=\"hljs-number\">7<\/span>]\n    print(x)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-6\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>You can also use the <code>readline()<\/code> method to <strong>read a file line by line, stop when you&#8217;ve gotten to the lines<\/strong> you want. Using this technique, we don&#8217;t need to read the entire file.<\/p>\n\n\n\n<p>Example 3:<\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code5\"  id=\"norun\" class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-7\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">lines = &#91;<span class=\"hljs-number\">2<\/span>, <span class=\"hljs-number\">5<\/span>]\nresult = &#91;]\ni = <span class=\"hljs-number\">0<\/span>\n\n<span class=\"hljs-keyword\">with<\/span> open(<span class=\"hljs-string\">\"read_demo.txt\"<\/span>, <span class=\"hljs-string\">\"r+\"<\/span>) <span class=\"hljs-keyword\">as<\/span> fp:\n    <span class=\"hljs-comment\"># access each line<\/span>\n    <span class=\"hljs-keyword\">while<\/span> <span class=\"hljs-literal\">True<\/span>:\n        line = fp.readline()\n        <span class=\"hljs-comment\"># check line number<\/span>\n        <span class=\"hljs-keyword\">if<\/span> i <span class=\"hljs-keyword\">in<\/span> lines:\n            result.append(line.strip())\n        <span class=\"hljs-comment\"># line number greater than needed exit the loop<\/span>\n        <span class=\"hljs-comment\"># lines&#91;-1] give last item from list<\/span>\n        <span class=\"hljs-keyword\">if<\/span> i &gt; lines&#91;<span class=\"hljs-number\">-1<\/span>]:\n            <span class=\"hljs-keyword\">break<\/span>;\n        i = i + <span class=\"hljs-number\">1<\/span>\nprint(result)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-7\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code5', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><\/div>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-generator-to-read-lines-from-a-file-by-line-number\">Generator to Read Lines from a file by line number<\/h2>\n\n\n\n<p>A fast and compact solution could be a generator expression to read a file using the line numbers.<\/p>\n\n\n\n<p><strong>If the number of lines to be returned from a file vast<\/strong>, you should use the generator.<\/p>\n\n\n\n<p>This solution accepts file pointer and line numbers to be read returns a generator object to iterate using a loop to get each line.<\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code6\"  class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-8\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-comment\"># read by line numbers<\/span>\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">def<\/span> <span class=\"hljs-title\">get_lines<\/span><span class=\"hljs-params\">(fp, line_numbers)<\/span>:<\/span>\n    <span class=\"hljs-keyword\">return<\/span> (x <span class=\"hljs-keyword\">for<\/span> i, x <span class=\"hljs-keyword\">in<\/span> enumerate(fp) <span class=\"hljs-keyword\">if<\/span> i <span class=\"hljs-keyword\">in<\/span> line_numbers)\n\n<span class=\"hljs-keyword\">with<\/span> open(<span class=\"hljs-string\">r\"E:\\demos\\files\\read_demo.txt\"<\/span>, <span class=\"hljs-string\">'r'<\/span>) <span class=\"hljs-keyword\">as<\/span> fp:\n    <span class=\"hljs-comment\"># read line 4 and 7<\/span>\n    lines = get_lines(fp, &#91;<span class=\"hljs-number\">3<\/span>, <span class=\"hljs-number\">6<\/span>])\n    <span class=\"hljs-comment\"># print each line<\/span>\n    <span class=\"hljs-keyword\">for<\/span> line <span class=\"hljs-keyword\">in<\/span> lines:\n        print(line.strip())<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-8\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code6', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><button class=\"hljs-run-button\" onclick=\"run_code('code6');\"><i class=\"far fa-play-circle\" aria-hidden=\"true\"><\/i> Run<\/button><\/div>\n\n\n<p><strong>Output<\/strong>:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">Fourth line\nSeventh Line<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-for-loop-in-fileobject-to-read-specific-lines-in-python\">for Loop in <code>fileobject<\/code> to Read Specific Lines in Python<\/h2>\n\n\n\n<p><strong>If your file size is small<\/strong> and you are not concerned with performance, then use looping technique.<\/p>\n\n\n\n<ul><li>Use <a href=\"https:\/\/pynative.com\/python-for-loop\/\">for loop<\/a> to iterate each line from a <a href=\"https:\/\/pynative.com\/python-file-objects\/\">file object<\/a><\/li><li>Use the if condition in each iteration of a loop to check the line number. If it matches, then save that line into a list.<\/li><\/ul>\n\n\n\n<p><strong>Note<\/strong>: This will load entire file in memory.<\/p>\n\n\n\n<p><strong>Example<\/strong>:<\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code7\"  class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-9\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">lines = &#91;<span class=\"hljs-number\">2<\/span>, <span class=\"hljs-number\">5<\/span>]\nresult = &#91;]\ni = <span class=\"hljs-number\">0<\/span>\n\n<span class=\"hljs-keyword\">with<\/span> open(<span class=\"hljs-string\">\"read_demo.txt\"<\/span>, <span class=\"hljs-string\">\"r+\"<\/span>) <span class=\"hljs-keyword\">as<\/span> fp:\n    <span class=\"hljs-comment\"># access each line<\/span>\n    <span class=\"hljs-keyword\">for<\/span> line <span class=\"hljs-keyword\">in<\/span> fp:\n        <span class=\"hljs-comment\"># check line number<\/span>\n        <span class=\"hljs-keyword\">if<\/span> i <span class=\"hljs-keyword\">in<\/span> lines:\n            result.append(line.strip())\n        i = i + <span class=\"hljs-number\">1<\/span>\nprint(result)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-9\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code7', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><button class=\"hljs-run-button\" onclick=\"run_code('code7');\"><i class=\"far fa-play-circle\" aria-hidden=\"true\"><\/i> Run<\/button><\/div>\n\n\n<p><strong>Output<\/strong>:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">['Third line', 'Sixth Line']<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-conclusion\">Conclusion<\/h2>\n\n\n\n<ul><li>Use <code><strong>readlines()<\/strong><\/code> or <code>readline()<\/code> and loop to iterate lines from a file object if the file <strong>size is small<\/strong>.<\/li><li>Use linecache for a more clean solution. It is fast if you are reading repeatedly or reading different lines from multiple files.<\/li><li>Use a loop and <strong><code>enumerate()<\/code> for large files<\/strong> because we don&#8217;t need to load the entire file in memory.<\/li><\/ul>\n","protected":false},"excerpt":{"rendered":"<p>This article lets you know how to read a specific lines from a file by line number in Python. Steps To Read Specific Lines From A File Example: Read specific lines from file by line number The following code shows&nbsp;how to read a text file by line number in Python. See the attached file used [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[22,33],"tags":[34],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v22.6 (Yoast SEO v22.6) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Python Read Specific Lines From a File [5 Ways] &#8211; PYnative<\/title>\n<meta name=\"description\" content=\"Learn to read specific lines from a file by line number in Python using enumerate function and linecache module.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Read Specific Lines From a File in Python\" \/>\n<meta property=\"og:description\" content=\"Learn to read specific lines from a file by line number in Python using enumerate function and linecache module.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/\" \/>\n<meta property=\"og:site_name\" content=\"PYnative\" \/>\n<meta property=\"article:published_time\" content=\"2021-06-13T12:54:27+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2021-07-03T06:38:58+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/pynative.com\/wp-content\/uploads\/2021\/06\/sample_text_file-1.png\" \/>\n<meta name=\"author\" content=\"Vishal\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@PyNative\" \/>\n<meta name=\"twitter:site\" content=\"@PyNative\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Vishal\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"6 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/\"},\"author\":{\"name\":\"Vishal\",\"@id\":\"https:\/\/pynative.com\/#\/schema\/person\/64b55d5bde2265918c5a9931de4de71f\"},\"headline\":\"Read Specific Lines From a File in Python\",\"datePublished\":\"2021-06-13T12:54:27+00:00\",\"dateModified\":\"2021-07-03T06:38:58+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/\"},\"wordCount\":1001,\"commentCount\":4,\"publisher\":{\"@id\":\"https:\/\/pynative.com\/#\/schema\/person\/64b55d5bde2265918c5a9931de4de71f\"},\"image\":{\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/pynative.com\/wp-content\/uploads\/2021\/06\/sample_text_file-1.png\",\"keywords\":[\"File Handling\"],\"articleSection\":[\"Python\",\"Python File Handling\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#respond\"]}],\"accessibilityFeature\":[\"tableOfContents\"]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/\",\"url\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/\",\"name\":\"Python Read Specific Lines From a File [5 Ways] &#8211; PYnative\",\"isPartOf\":{\"@id\":\"https:\/\/pynative.com\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/pynative.com\/wp-content\/uploads\/2021\/06\/sample_text_file-1.png\",\"datePublished\":\"2021-06-13T12:54:27+00:00\",\"dateModified\":\"2021-07-03T06:38:58+00:00\",\"description\":\"Learn to read specific lines from a file by line number in Python using enumerate function and linecache module.\",\"breadcrumb\":{\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#primaryimage\",\"url\":\"https:\/\/pynative.com\/wp-content\/uploads\/2021\/06\/sample_text_file-1.png\",\"contentUrl\":\"https:\/\/pynative.com\/wp-content\/uploads\/2021\/06\/sample_text_file-1.png\",\"width\":450,\"height\":257,\"caption\":\"text file\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/pynative.com\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Python\",\"item\":\"https:\/\/pynative.com\/python\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"File Handling\",\"item\":\"https:\/\/pynative.com\/python\/file-handling\/\"},{\"@type\":\"ListItem\",\"position\":4,\"name\":\"Read Specific Lines From a File in Python\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/pynative.com\/#website\",\"url\":\"https:\/\/pynative.com\/\",\"name\":\"PYnative\",\"description\":\"Python Programming\",\"publisher\":{\"@id\":\"https:\/\/pynative.com\/#\/schema\/person\/64b55d5bde2265918c5a9931de4de71f\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/pynative.com\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"en-US\"},{\"@type\":[\"Person\",\"Organization\"],\"@id\":\"https:\/\/pynative.com\/#\/schema\/person\/64b55d5bde2265918c5a9931de4de71f\",\"name\":\"Vishal\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/pynative.com\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/pynative.com\/wp-content\/uploads\/2019\/01\/vishalHule.jpg\",\"contentUrl\":\"https:\/\/pynative.com\/wp-content\/uploads\/2019\/01\/vishalHule.jpg\",\"width\":968,\"height\":1065,\"caption\":\"Vishal\"},\"logo\":{\"@id\":\"https:\/\/pynative.com\/#\/schema\/person\/image\/\"},\"description\":\"Founder of PYnative.com. I am a Python developer and I love to write articles to help developers. | All the best for your future Python endeavors!\",\"sameAs\":[\"https:\/\/pynative.com\"]},{\"@type\":\"HowTo\",\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#howto-1\",\"name\":\"Read Specific Lines From a File in Python\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#article\"},\"description\":\"Let's assume the file to read is significantly large (in GB), and you don't want to read the whole file in memory at once but only want to jump and read lines #5 and #120. To read specific lines from a text file, Please follow these steps:\",\"step\":[{\"@type\":\"HowToStep\",\"url\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#how-to-step-1623072196137\",\"name\":\"Open file in Read Mode\",\"itemListElement\":[{\"@type\":\"HowToDirection\",\"text\":\"To <a href=\\\"https:\/\/pynative.com\/python-file-open\/\\\">open a file<\/a> pass file path and access mode r to the open() function. The access mode specifies the operation you wanted to perform on the file, such as reading or writing.<br\/>For example, fp= open(r'File_Path', 'r') to <a href=\\\"https:\/\/pynative.com\/python-read-file\/\\\">read a file<\/a>.\"}]},{\"@type\":\"HowToStep\",\"url\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#how-to-step-1623726533105\",\"name\":\"Create a list to store line numbers\",\"itemListElement\":[{\"@type\":\"HowToDirection\",\"text\":\"Create a <a href=\\\"https:\/\/pynative.com\/python-lists\/\\\">list<\/a> with the number of each line in a text file to read. <br\/>For example, line_numbers = [4, 7]. Here we are reading lines 4 and 7.\"}]},{\"@type\":\"HowToStep\",\"url\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#how-to-step-1623142924301\",\"name\":\"Create a list to store lines\",\"itemListElement\":[{\"@type\":\"HowToDirection\",\"text\":\"After reading line 4 and 7 we will store result it in a list variable.\"}]},{\"@type\":\"HowToStep\",\"url\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#how-to-step-1623072253286\",\"name\":\"Use for loop with enumerate() function to get a line and its number.\",\"itemListElement\":[{\"@type\":\"HowToDirection\",\"text\":\"The <a href=\\\"https:\/\/docs.python.org\/3\/library\/functions.html#enumerate\\\">enumerate()<\/a> function adds a counter to an iterable and returns it in enumerate object. Pass the file pointer returned by the open() function to the enumerate(). <br\/>We can use this enumerate object with a <a href=\\\"https:\/\/pynative.com\/python-for-loop\/\\\">for loop<\/a> to access the line number.<br\/><strong>Note<\/strong>: enumerate(file_pointer) doesn't load the entire file in memory, so this is an efficient solution.\"}]},{\"@type\":\"HowToStep\",\"url\":\"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#how-to-step-1623142058359\",\"name\":\"Read file by line number\",\"itemListElement\":[{\"@type\":\"HowToDirection\",\"text\":\"Use the if condition in each iteration of a loop to check the line number. If it matches, then save that line into a list.\"}]}],\"inLanguage\":\"en-US\"}]}<\/script>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"Python Read Specific Lines From a File [5 Ways] &#8211; PYnative","description":"Learn to read specific lines from a file by line number in Python using enumerate function and linecache module.","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:\/\/pynative.com\/python-read-specific-lines-from-a-file\/","og_locale":"en_US","og_type":"article","og_title":"Read Specific Lines From a File in Python","og_description":"Learn to read specific lines from a file by line number in Python using enumerate function and linecache module.","og_url":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/","og_site_name":"PYnative","article_published_time":"2021-06-13T12:54:27+00:00","article_modified_time":"2021-07-03T06:38:58+00:00","og_image":[{"url":"https:\/\/pynative.com\/wp-content\/uploads\/2021\/06\/sample_text_file-1.png"}],"author":"Vishal","twitter_card":"summary_large_image","twitter_creator":"@PyNative","twitter_site":"@PyNative","twitter_misc":{"Written by":"Vishal","Est. reading time":"6 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#article","isPartOf":{"@id":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/"},"author":{"name":"Vishal","@id":"https:\/\/pynative.com\/#\/schema\/person\/64b55d5bde2265918c5a9931de4de71f"},"headline":"Read Specific Lines From a File in Python","datePublished":"2021-06-13T12:54:27+00:00","dateModified":"2021-07-03T06:38:58+00:00","mainEntityOfPage":{"@id":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/"},"wordCount":1001,"commentCount":4,"publisher":{"@id":"https:\/\/pynative.com\/#\/schema\/person\/64b55d5bde2265918c5a9931de4de71f"},"image":{"@id":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#primaryimage"},"thumbnailUrl":"https:\/\/pynative.com\/wp-content\/uploads\/2021\/06\/sample_text_file-1.png","keywords":["File Handling"],"articleSection":["Python","Python File Handling"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#respond"]}],"accessibilityFeature":["tableOfContents"]},{"@type":"WebPage","@id":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/","url":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/","name":"Python Read Specific Lines From a File [5 Ways] &#8211; 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I am a Python developer and I love to write articles to help developers. | All the best for your future Python endeavors!","sameAs":["https:\/\/pynative.com"]},{"@type":"HowTo","@id":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#howto-1","name":"Read Specific Lines From a File in Python","mainEntityOfPage":{"@id":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#article"},"description":"Let's assume the file to read is significantly large (in GB), and you don't want to read the whole file in memory at once but only want to jump and read lines #5 and #120. To read specific lines from a text file, Please follow these steps:","step":[{"@type":"HowToStep","url":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#how-to-step-1623072196137","name":"Open file in Read Mode","itemListElement":[{"@type":"HowToDirection","text":"To <a href=\"https:\/\/pynative.com\/python-file-open\/\">open a file<\/a> pass file path and access mode r to the open() function. The access mode specifies the operation you wanted to perform on the file, such as reading or writing.<br\/>For example, fp= open(r'File_Path', 'r') to <a href=\"https:\/\/pynative.com\/python-read-file\/\">read a file<\/a>."}]},{"@type":"HowToStep","url":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#how-to-step-1623726533105","name":"Create a list to store line numbers","itemListElement":[{"@type":"HowToDirection","text":"Create a <a href=\"https:\/\/pynative.com\/python-lists\/\">list<\/a> with the number of each line in a text file to read. <br\/>For example, line_numbers = [4, 7]. Here we are reading lines 4 and 7."}]},{"@type":"HowToStep","url":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#how-to-step-1623142924301","name":"Create a list to store lines","itemListElement":[{"@type":"HowToDirection","text":"After reading line 4 and 7 we will store result it in a list variable."}]},{"@type":"HowToStep","url":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#how-to-step-1623072253286","name":"Use for loop with enumerate() function to get a line and its number.","itemListElement":[{"@type":"HowToDirection","text":"The <a href=\"https:\/\/docs.python.org\/3\/library\/functions.html#enumerate\">enumerate()<\/a> function adds a counter to an iterable and returns it in enumerate object. Pass the file pointer returned by the open() function to the enumerate(). <br\/>We can use this enumerate object with a <a href=\"https:\/\/pynative.com\/python-for-loop\/\">for loop<\/a> to access the line number.<br\/><strong>Note<\/strong>: enumerate(file_pointer) doesn't load the entire file in memory, so this is an efficient solution."}]},{"@type":"HowToStep","url":"https:\/\/pynative.com\/python-read-specific-lines-from-a-file\/#how-to-step-1623142058359","name":"Read file by line number","itemListElement":[{"@type":"HowToDirection","text":"Use the if condition in each iteration of a loop to check the line number. If it matches, then save that line into a list."}]}],"inLanguage":"en-US"}]}},"featured_image_src":null,"featured_image_src_square":null,"author_info":{"display_name":"Vishal","author_link":"https:\/\/pynative.com\/author\/vishal\/"},"_links":{"self":[{"href":"https:\/\/pynative.com\/wp-json\/wp\/v2\/posts\/9556"}],"collection":[{"href":"https:\/\/pynative.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pynative.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pynative.com\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/pynative.com\/wp-json\/wp\/v2\/comments?post=9556"}],"version-history":[{"count":0,"href":"https:\/\/pynative.com\/wp-json\/wp\/v2\/posts\/9556\/revisions"}],"wp:attachment":[{"href":"https:\/\/pynative.com\/wp-json\/wp\/v2\/media?parent=9556"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pynative.com\/wp-json\/wp\/v2\/categories?post=9556"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pynative.com\/wp-json\/wp\/v2\/tags?post=9556"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}