Taking a File and Reading It Python

Summary: in this tutorial, you larn various ways to read text files in Python.

TL;DR

The post-obit 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 follow these steps:

• Get-go, open a text file for reading by using the open() function.
• Second, read text from the text file using the file read(), readline(), or readlines() method of the file object.
• Tertiary, shut the file using the file close() method.

1) open up() office

The open up() function has many parameters but you'll be focusing on the offset two.

            
              open up(path_to_file, way)            
          

The path_to_file parameter specifies the path to the text file.

If the file is in the same folder as the program, you just need to specify the name of the file. Otherwise, yous need to specify the path to the file.

To specify the path to the file, yous use the forwards-slash ('/') fifty-fifty if y'all're working in Windows.

For example, if the file is readme.txt stored in the sample binder as the program, yous demand to specify the path to the file as c:/sample/readme.txt

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

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

Manner	Description
'r'	Open for text file for reading text
'due west'	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 folder every bit the program, you employ the following lawmaking:

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

The open() function returns a file object which y'all will employ to read text from a text file.

two) 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 cord. This method is useful if y'all have a small file and you desire to manipulate the whole text of that file.
• readline() – read the text file line by line and render all the lines every bit strings.
• readlines() – read all the lines of the text file and return them as a listing of strings.

3) close() method

The file that you open will remain open until y'all shut information technology using the close() method.

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

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

            
                              f                .shut()            
                          Code linguistic communication:              CSS              (              css              )                      

To shut 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()            
                          Code language:              JavaScript              (              javascript              )                      

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

Reading a text file examples

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

The following example 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 up('the-zen-of-python.txt')                as                f:     contents = f.read()     print(contents)            
                          Code language:              JavaScript              (              javascript              )                      

Output:

            
              Beautiful is better than ugly. Explicit is better than implicit. Simple is better than complex. ...                          
          

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

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

Output:

            
              line 1: Cute is improve than ugly.  line 2: Explicit is meliorate than implicit.  line 3: Simple is better than complex. ...                          
          

The following instance shows how to use the readline() to read the text file line past line:

            
                              with                open('the-zen-of-python.txt')                as                f:     line = f.readline()                while                line:         line = f.readline()         impress(line)            
                          Code linguistic communication:              JavaScript              (              javascript              )                      

Output:

            
              Explicit is improve than implicit.  Simple is better than circuitous.  Complex is meliorate than complicated. ...                          
          

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

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

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

This is more than concise manner 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 uncomplicated ASCII text file. And it's likely a UTF-8 file that uses more than than simply the standard ASCII text characters.

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

For the demonstration, you'll use the following 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 up() function with the 'r' way to open a text file for reading.
• Use the read(), readline(), or readlines() method to read a text file.
• Always close a file after completing reading it 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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