How to Read a File , by , in Python

Summary: in this tutorial, yous learn diverse ways to read text files in Python.

TL;DR

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

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

Steps for reading a text file in Python

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

• First, open up a text file for reading by using the open up() function.
• Second, read text from the text file using the file read(), readline(), or readlines() method of the file object.
• Third, close the file using the file close() method.

1) open up() office

The open() office has many parameters but you'll be focusing on the first two.

            
              open(path_to_file, mode)            
          

The path_to_file parameter specifies the path to the text file.

If the file is in the same folder every bit the program, you simply demand to specify the proper name of the file. Otherwise, you need to specify the path to the file.

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

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

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

The following table shows available modes for opening a text file:

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

For example, to open a file whose proper noun is the-zen-of-python.txt stored in the same folder as the program, y'all employ the following code:

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

The open() function returns a file object which you will apply 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 y'all have 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 equally strings.
• readlines() – read all the lines of the text file and return them as a list of strings.

3) close() method

The file that you open volition remain open up until you lot close it using the close() method.

It's important to close the file that is no longer in apply. If you don't close the file, the program may crash or the file would be corrupted.

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

            
                              f                .shut()            
                          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)                as                f:     contents = f.readlines()            
                          Lawmaking language:              JavaScript              (              javascript              )                      

In practise, you'll use the with statement to close the file automatically.

Reading a text file examples

Nosotros'll use the-zen-of-python.txt file for the demonstration.

The following case illustrates how to utilise 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')                as                f:     contents = f.read()     print(contents)            
                          Code linguistic communication:              JavaScript              (              javascript              )                      

Output:

            
              Cute is better than ugly. Explicit is ameliorate than implicit. Simple is improve than circuitous. ...                          
          

The following example 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')                every bit                f:     lines = f.readlines()  count =                0                for                line                in                lines:     count +=                ane                print(f'line {count}: {line}')                          
                          Code language:              JavaScript              (              javascript              )                      

Output:

            
              line ane: Beautiful is amend than ugly.  line 2: Explicit is better than implicit.  line iii: Uncomplicated is better than complex. ...                          
          

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

            
                              with                open('the-zen-of-python.txt')                every bit                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 circuitous.  Complex is better than complicated. ...                          
          

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

The open() part returns a file object which is an iterable object. Therefore, you lot can use a for loop to iterate over the lines of a text file as follows:

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

This is more concise way to read a text file line by line.

Read UTF-8 text files

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

To open a UTF-viii text file, you need to laissez passer the encoding='utf-8' to the open() part to instruct information technology to look UTF-8 characters from the file.

For the demonstration, you'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('quotes.txt', encoding='utf8')                as                f:                for                line                in                f:         print(line.strip())                          
                          Code linguistic communication:              JavaScript              (              javascript              )                      

Output:

Summary

• Use the open() function with the 'r' way to open a text file for reading.
• Use the read(), readline(), or readlines() method to read a text file.
• Ever shut a file after completing reading it using the close() method or the with statement.
• Utilize the encoding='utf-eight' to read the UTF-eight text file.

Did you lot find this tutorial helpful ?

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

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