Python Read N Lines at a Time

Tabular array of Contents Hide

1. Steps to Read Text File in Python
   1. Python open() function
   2. Methods for Reading file contents
   3. Python shut() function
2. Examples for Reading a Text file in Python
   1. Example 1 – Read the entire text file using the read() function
   2. Instance two – Read the specific length of characters in a text file using the read() function
   3. Example three – Read a single line in a file using the readline() role
   4. Instance 4- Read text file line by line using the readline() function
   5. Example 5 – Read all the lines as a list in a file using the readlines() function

Python provides built-in functions to perform file operations, such as creating, reading, and writing files. There are mainly two types of files that Python tin can handle, normal text files and binary files. In this tutorial, we volition take a look at how to read text files in Python.

Steps to Read Text File in Python

In Python, to read a text file, you need to follow the below steps.

Step one: The file needs to be opened for reading using the open() method and pass a file path to the function.

Step ii: The next step is to read the file, and this can be achieved using several built-in methods such equally read() , readline() , readlines() .

Step 3: Once the read operation is performed, the text file must be closed using the close() office.

Now that we have seen the steps to read the file content let's sympathize each of these methods before getting into examples.

Python open up() role

The open() function opens the file if possible and returns the corresponding file object.

Syntax – open(file, mode='r', buffering=-i, encoding=None, errors=None, newline=None, closefd=Truthful, opener=None)

The open() function has a lot of parameters. Let'due south take a look at the necessary params for reading the text file. It opens the file in a specified mode and returns a file object.

Parameters

• file – path like object which represents the file path
• mode (Optional) – The manner is an optional parameter. It'southward a string that specifies the mode in which you want to open the file.

Style	Description
'r'	Open a file for read manner (default if manner is not specified)
'w'	Open up a file for writing. Python will create a new file if does not exist or truncates a file content if file exists
'x'	Open a file for exclusive creation.
'a'	Open up a file for appending the text. Creates a new file if file does not exist.
't'	Open a file in text manner. (default)
'b'	Open a file in binary mode.
'+'	Open a file for updating (reading and writing)

Example

              file = open('C:\hello.txt','r')            

Methods for Reading file contents

In that location are three ways to read data from a text file.

1. read() : The read() function returns the read bytes in the grade of cord. This method is useful when you have a pocket-sized file, and you want to read the specified bytes or entire file and store it into a string variable.
2. readline() : The readline() function returns one line from a text file and retuns in the grade of string.
3. readlines() : The readlines() function reads all the lines from the text file and returns each line as a string chemical element in a listing.

Python close() function

The file will remain open up until you lot close the file using the close() function. It is a must and all-time practice to perform this performance after reading the data from the file every bit it frees up the retention space acquired past that file. Otherwise, information technology may crusade an unhandled exception.

Examples for Reading a Text file in Python

Case 1 – Read the entire text file using the read() function

In the below case, we are reading the entire text file using the read() method. The file can exist opened in the read mode or in a text mode to read the information, and information technology tin exist stored in the string variable.

              # Programme to read the unabridged file using read() function file = open("python.txt", "r") content = file.read() print(content) file.close()   # Plan to read the entire file (absolute path) using read() function file = open("C:/Projects/Tryouts/python.txt", "r") content = file.read() print(content) file.shut()            

Output

              Love User,  Welcome to Python Tutorial  Have a neat learning !!!  Thank you            

Example 2 – Read the specific length of characters in a text file using the read() function

At that place are times where you need to read the specific bytes in a file. In that case, y'all can utilize the read() office past specifying the bytes. The method volition output only the specified bytes of characters in a file, as shown below.

              # Programme to read the specific length  # of characters in a file using read() function file = open("python.txt", "r") content = file.read(20) print(content) file.close()                          

Output

              Honey User,  Welcome            

Instance 3 – Read a unmarried line in a file using the readline() function

If you want to read a single line in a file, then you lot could achieve this using readline() function. Y'all also use this method to retrieve specific bytes of characters in a line, similar to the read() method.

              # Program to read single line in a file using readline() part file = open("python.txt", "r") content = file.readline() print(content) file.close()            

Output

              Honey User,                          

Case iv- Read text file line by line using the readline() function

If you want to traverse the file line past line and output in any format, then you could apply the while loop with the readline() method every bit shown below. This is the most constructive style to read the text file line by line in Python.

              # Programme to read all the lines in a file using readline() function file = open("python.txt", "r") while True: 	content=file.readline() 	if not content: 		break 	print(content) file.close()                          

Output

              Dear User,  Welcome to Python Tutorial  Have a great learning !!!  Thanks            

Example five – Read all the lines as a list in a file using the readlines() function

The readlines() method will read all the lines in the file and outputs in a list of strings, every bit shown below. Later you can use the list to traverse and excerpt the specified content from the list.

              # Programme to read all the lines as a listing in a file #  using readlines() function  file = open("python.txt", "r") content=file.readlines() print(content) file.close()                          

Output

              ['Love User,\n', 'Welcome to Python Tutorial\n', 'Have a great learning !!!\due north', 'Thanks']            

Related Tags

• close(),
• style,
• open(),
• read file content,
• read(),
• readline(),
• readlines()

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