How to Read a List of Numbers From a File in Python

Summary: in this tutorial, y'all learn diverse 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 up('readme.txt')                as                f:     lines = f.readlines()            
                          Code language:              JavaScript              (              javascript              )                      

Steps for reading a text file in Python

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

• Showtime, open 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, shut the file using the file close() method.

ane) open up() role

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

            
              open up(path_to_file, style)            
          

The path_to_file parameter specifies the path to the text file.

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

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

For example, if the file is readme.txt stored in the sample folder every bit the plan, you 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 post-obit table shows available modes for opening a text file:

Mode	Description
'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 name is the-zen-of-python.txt stored in the aforementioned binder as the program, you employ the following code:

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

The open up() function returns a file object which you will apply to read text from a text file.

ii) 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 have a small-scale file and you want to manipulate the whole text of that file.
• readline() – read the text file line by line and render all the lines as strings.
• readlines() – read all the lines of the text file and return them as a listing of strings.

3) shut() method

The file that you open will remain open until you close it 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 program may crash or the file would be corrupted.

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

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

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

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

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

Reading a text file examples

We'll use 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 cord:

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

Output:

            
              Beautiful is ameliorate than ugly. Explicit is improve than implicit. Simple is meliorate than complex. ...                          
          

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

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

Output:

            
              line i: Cute is better than ugly.  line 2: Explicit is better than implicit.  line 3: Uncomplicated is better than complex. ...                          
          

The following 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 improve than implicit.  Simple is amend than circuitous.  Complex is amend than complicated. ...                          
          

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

The open up() part returns a file object which is an iterable object. Therefore, you can apply 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 than concise fashion to read a text file line past line.

Read UTF-8 text files

The lawmaking 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 non a elementary ASCII text file. And it's likely a UTF-viii file that uses more than just the standard ASCII text characters.

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

For the demonstration, you'll use the following quotes.txt file that contains some quotes in Japanese.

The post-obit shows how to loop through the quotes.txt file:

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

Output:

Summary

• Use the open() function with the 'r' fashion to open a text file for reading.
• Use the read(), readline(), or readlines() method to read a text file.
• Always shut a file later completing reading information technology using the close() method or the with argument.
• 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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