Open and Read a File via Python Command Prompt

Summary: in this tutorial, you lot 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')                as                f:     lines = f.readlines()            
                          Code linguistic communication:              JavaScript              (              javascript              )                      

Steps for reading a text file in Python

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

• First, 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.
• Third, close the file using the file close() method.

1) open() function

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

            
              open up(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 lot 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 forrad-slash ('/') even if you're working in Windows.

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

The style is an optional parameter. Information technology's a cord that specifies the manner in which you desire to open the file.

The post-obit tabular array shows available modes for opening a text file:

Mode	Description
'r'	Open up for text file for reading text
'w'	Open a text file for writing text
'a'	Open up 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 as the plan, you use the post-obit code:

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

The open() part 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 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 lot take a small file and you lot want to dispense 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 list of strings.

iii) close() method

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

It's of import to shut 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 telephone call the shut() method to close 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 up(path_to_file)                equally                f:     contents = f.readlines()            
                          Code language:              JavaScript              (              javascript              )                      

In exercise, 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 post-obit instance 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()     impress(contents)            
                          Code language:              JavaScript              (              javascript              )                      

Output:

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

The following example 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 +=                1                print(f'line {count}: {line}')                          
                          Code language:              JavaScript              (              javascript              )                      

Output:

            
              line 1: Beautiful is better than ugly.  line two: Explicit is better than implicit.  line 3: Unproblematic is amend than complex. ...                          
          

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

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

Output:

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

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

The open up() 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 equally 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 information technology'due south likely a UTF-8 file that uses more than but the standard ASCII text characters.

To open a UTF-8 text file, y'all need to pass the encoding='utf-viii' to the open() function to instruct it to wait 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())                          
                          Lawmaking language:              JavaScript              (              javascript              )                      

Output:

Summary

• Apply the open() function with the 'r' mode to open up a text file for reading.
• Use the read(), readline(), or readlines() method to read a text file.
• Ever shut a file afterward completing reading it using the close() method or the with statement.
• Apply the encoding='utf-8' to read the UTF-viii text file.

Did y'all find this tutorial helpful ?

Open and Read a File via Python Command Prompt

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

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