How to Read Numbers From File 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 string:

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

Steps for reading a text file in Python

To read a text file in Python, y'all follow these steps:

• First, open up a text file for reading by using the open() function.
• 2nd, 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 shut() method.

1) open() function

The open() function has many parameters but yous'll be focusing on the beginning two.

            
              open(path_to_file, manner)            
          

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 proper name of the file. Otherwise, y'all demand to specify the path to the file.

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

For case, if the file is readme.txt stored in the sample binder as the program, y'all 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 mode in which you want to open the file.

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

Mode	Clarification
'r'	Open for text file for reading text
'west'	Open a text file for writing text
'a'	Open a text file for appending text

For example, to open a file whose proper name is the-zen-of-python.txt stored in the same folder equally the program, y'all use the post-obit lawmaking:

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

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

2) Reading text methods

The file object provides yous with iii methods for reading text from a text file:

• read() – read all text from a file into a string. This method is useful if you have a modest file and you want to manipulate the whole text of that file.
• readline() – read the text file line past line and render all the lines every bit 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 will remain open until y'all shut information technology using the shut() method.

It's important to shut 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 post-obit shows how to phone 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 argument similar this:

            
                              with                open(path_to_file)                as                f:     contents = f.readlines()            
                          Code language:              JavaScript              (              javascript              )                      

In practice, you'll employ the with statement to shut the file automatically.

Reading a text file examples

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

The post-obit example 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')                every bit                f:     contents = f.read()     print(contents)            
                          Lawmaking language:              JavaScript              (              javascript              )                      

Output:

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

The following example uses the readlines() method to read the text file and returns the file contents equally a list of strings:

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

Output:

            
              line 1: Cute is better than ugly.  line 2: Explicit is better than implicit.  line three: Simple is better than complex. ...                          
          

The post-obit case shows how to use the readline() to read the text file line by line:

            
                              with                open('the-zen-of-python.txt')                as                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 amend than complicated. ...                          
          

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

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

            
                              with                open up('the-zen-of-python.txt')                as                f:                for                line                in                f:         print(line)            
                          Lawmaking 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. Withal, if you're dealing with other languages such equally Japanese, Chinese, and Korean, the text file is not a simple ASCII text file. And it's probable a UTF-viii file that uses more than only the standard ASCII text characters.

To open a UTF-8 text file, you need to laissez passer the encoding='utf-eight' to the open() function to instruct it to wait UTF-8 characters from the file.

For the demonstration, y'all'll utilise 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 language:              JavaScript              (              javascript              )                      

Output:

Summary

• Use the open up() role with the 'r' way to open up a text file for reading.
• Employ the read(), readline(), or readlines() method to read a text file.
• Always close a file after completing reading information technology using the close() method or the with statement.
• Use the encoding='utf-viii' 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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