Read Text File Line by Line Python

Summary: in this tutorial, y'all learn various ways to read text files in Python.

TL;DR

The following shows how to read all texts from the readme.txt file into a cord:

            
                              with                open('readme.txt')                every bit                f:     lines = f.readlines()            
                          Lawmaking language:              JavaScript              (              javascript              )                      

Steps for reading a text file in Python

To read a text file in Python, you follow these steps:

• Starting time, open up a text file for reading past using the open() function.
• Second, read text from the text file using the file read(), readline(), or readlines() method of the file object.
• 3rd, close the file using the file close() method.

1) open() function

The open() function has many parameters but you'll exist focusing on the first 2.

            
              open(path_to_file, mode)            
          

The path_to_file parameter specifies the path to the text file.

If the file is in the aforementioned folder every bit the program, y'all just demand to specify the name of the file. Otherwise, you need to specify the path to the file.

To specify the path to the file, you use the forward-slash ('/') even if you're working in Windows.

For example, if the file is readme.txt stored in the sample folder equally the program, you need to specify the path to the file as c:/sample/readme.txt

The style is an optional parameter. It's a string that specifies the fashion in which yous want to open the file.

The post-obit table shows bachelor modes for opening a text file:

Mode	Description
'r'	Open for text file for reading text
'w'	Open a text file for writing text
'a'	Open a text file for appending text

For example, to open a file whose name is the-zen-of-python.txt stored in the aforementioned binder as the programme, you utilize the post-obit code:

            
                              f = open up('the-zen-of-python.txt','r')            
                          Code language:              JavaScript              (              javascript              )                      

The open() function returns a file object which you volition utilize to read text from a text file.

2) Reading text methods

The file object provides you with three methods for reading text from a text file:

• read() – read all text from a file into a string. This method is useful if you take a small file and you want to manipulate the whole text of that file.
• readline() – read the text file line by line and return all the lines as strings.
• readlines() – read all the lines of the text file and return them every bit a list of strings.

3) close() method

The file that you open up will remain open until you shut it using the shut() method.

Information technology's of import to close the file that is no longer in use. If you don't shut the file, the program may crash or the file would exist corrupted.

The following shows how to telephone call the shut() method to shut the file:

            
                              f                .close()            
                          Code language:              CSS              (              css              )                      

To close the file automatically without calling the close() method, you use the with statement like this:

            
                              with                open(path_to_file)                every bit                f:     contents = f.readlines()            
                          Code linguistic communication:              JavaScript              (              javascript              )                      

In practice, y'all'll utilize the with statement to close the file automatically.

Reading a text file examples

We'll employ the-zen-of-python.txt file for the sit-in.

The following case illustrates how to use the read() method to read all the contents of the the-zen-of-python.txt file into a string:

            
                              with                open('the-zen-of-python.txt')                every bit                f:     contents = f.read()     impress(contents)            
                          Code language:              JavaScript              (              javascript              )                      

Output:

            
              Beautiful is improve than ugly. Explicit is amend than implicit. Uncomplicated is better than circuitous. ...                          
          

The post-obit instance uses the readlines() method to read the text file and returns the file contents every bit a list of strings:

            
              lines = []                with                open('the-zen-of-python.txt')                as                f:     lines = f.readlines()  count =                0                for                line                in                lines:     count +=                1                print(f'line {count}: {line}')                          
                          Code linguistic communication:              JavaScript              (              javascript              )                      

Output:

            
              line 1: Beautiful is better than ugly.  line ii: Explicit is improve than implicit.  line three: Simple is better than circuitous. ...                          
          

The following example shows how to apply the readline() to read the text file line by line:

            
                              with                open('the-zen-of-python.txt')                equally                f:     line = f.readline()                while                line:         line = f.readline()         print(line)            
                          Code language:              JavaScript              (              javascript              )                      

Output:

            
              Explicit is better than implicit.  Simple is better than complex.  Complex is better than complicated. ...                          
          

A more curtailed way to read a text file line by line

The open up() function returns a file object which is an iterable object. Therefore, you lot tin use a for loop to iterate over the lines of a text file every bit follows:

            
                              with                open up('the-zen-of-python.txt')                as                f:                for                line                in                f:         impress(line)            
                          Code language:              JavaScript              (              javascript              )                      

This is more than curtailed fashion to read a text file line past line.

Read UTF-8 text files

The code in the previous examples works fine with ASCII text files. Still, if you're dealing with other languages such as Japanese, Chinese, and Korean, the text file is not a simple ASCII text file. And it'due south likely a UTF-8 file that uses more than just the standard ASCII text characters.

To open a UTF-8 text file, you need to pass the encoding='utf-eight' to the open() part to instruct it to expect UTF-8 characters from the file.

For the sit-in, y'all'll use the post-obit quotes.txt file that contains some quotes in Japanese.

The following shows how to loop through the quotes.txt file:

            
                              with                open up('quotes.txt', encoding='utf8')                as                f:                for                line                in                f:         print(line.strip())                          
                          Code language:              JavaScript              (              javascript              )                      

Output:

Summary

• Use the open() function with the 'r' mode to open a text file for reading.
• Use the read(), readline(), or readlines() method to read a text file.
• Always close a file later on completing reading information technology using the close() method or the with statement.
• Use the encoding='utf-8' to read the UTF-8 text file.

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Source: https://www.pythontutorial.net/python-basics/python-read-text-file/

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