How to use seek() method to reset a file read/write position in Python?

In Python file handling, there are several functions and methods that have different functionalities and are used to achieve specific purposes and tasks. Among such kind as above, the seek() method makes it possible for you to reset the read/write position within a file. This functionality of the method is very helpful when you need to move the cursor to a specific or particular location in the file to carry out subsequent read or write operations. In this article, we will examine several ways how you can make use of the seek() method to reset the read/write position in Python. You can follow the easy-to-comprehend explanations and code examples given below to master the concepts and practices of resetting read and write positions in a file.

Resetting the Read Position to the Beginning of the File

To be able to reset the read position to the beginning of the file, you follow the steps given below

• Step 1: You start by opening the file in read mode using the open() function.

• Step 2: You then go on to assign the returned file object to a variable.

• Step 3: You next use the seek() method with an offset of 0 as the argument to reset the read position to the beginning of the file.

• Step 4: You, finally, can read the content from the new position using the read() method.

Example

Assuming there is a file myfile.txt with following content

#myfile.txt
This is a test file

# Open the file in read mode
file = open('myfile.txt', 'r')

# Reset the read position to the beginning of the file
file.seek(0)

# Read the content from the new position
content = file.read()

# Print the content
print("Content:", content)

# Close the file
file.close()

When above code is run, and the file myfile.txt is opened we get the following

Output

This is a test file

Resetting the Write Position to the Beginning of the File

By following the steps given below, you will be able to reset the write position to the beginning of the file.

• Step 1: You begin by opening the file in write mode using the open() function.

• Step 2: You go on to assign the returned file object to a variable.

• Step 3: You then use the seek() method with an offset of 0 as the argument to reset the write position to the beginning of the file.

• Step 4: Lastly, you write the desired content using the write() method.

Example

Assuming there is a file myfile.txt with following content

#myfile.txt
This is a test file

# Open the file in write mode
file = open('myfile.txt', 'w')

# Reset the write position to the beginning of the file
file.seek(0)

# Write new content at the write position
file.write("This is new content.")

# Close the file
file.close()

When above code is run, and the file myfile.txt is opened we get the following

Output

This is new content.

Resetting the Read/Write Position to a Specific Location

There are alternate ways of achieving the same purpose; you can also reset the read/write position to a specific location within the file by providing the desired offset value to the seek() method. Let us look at an example:

Example

Assuming there is a file myfile.txt with the following content

#myfile.txt
This is a test file

# Open the file in read and write mode
file = open('myfile.txt', 'r+')

# Reset the read/write position to a specific location (e.g., 15th character)
file.seek(15)

# Perform read or write operations at the new position
content = file.read()
print("Content:", content)

# Close the file
file.close()

When the above code is run, and the file myfile.txt is opened we get the following

Output

Content: file.

Resetting the Read Position Relative to the Current Position

• Step 1: You start by opening the file in read mode using the open() function.

• Step 2: You move on to assign the returned file object to a variable.

• Step 3: You next make use of the seek() method with a positive or negative offset value to move the read position forward or backward from the current position.

• Step 4: Finally, you read the content from the new position using the read() method.

Example

Assuming there is a file myfile.txt with following content

#myfile.txt
This is a test file

# Open the file in read mode
file = open('myfile.txt', 'r')

# Move the read position 5 characters forward from the start position
file.seek(5, 0)

# Read the content from the new position
content = file.read()

# Print the content
print("Content:", content)

# Close the file
file.close()

Output

Content: is a test file.

Resetting the Write Position Relative to the Current Position

It is better to follow the steps given below to reset the write position relative to the current position within a file.

Example

Here, in this example, we begin by first opening the file in read mode and reading its entire content into the content variable. Then we go on to close the file. We modify the content of the file by inserting the desired new content at the desired position (in this case, 10 bytes from the beginning). At last, we open the file in write mode, write the modified content back into the file, and close it.

Assuming there is a file myfile.txt with the following content

#myfile.txt
This is a test file

# Open the file in read mode
file = open('myfile.txt', 'r')
content = file.read()
file.close()

# Modify the content
new_content = content[:10] + "New content" + content[10:]

# Open the file in write mode
file = open('myfile.txt', 'w')

file.write(new_content)
file.close()

When above code is run, and the file myfile.txt is opened we get the following

Output

This is a New contenttest file.

In Python file handling, the process of resetting the read/write position within a file is of great importance when you want to navigate to a certain location for read or write operations later. In this article, we have given some examples that showcased how to use the seek() method to reset the read/write position in Python. We also gave additional examples that clearly dwelt on how to reset the read/write position using the seek() method with relative offset values. By following the lucid and clear explanations and code snippets, you can certainly expand your understanding of the skill of resetting the read/write position in a file. It is best never to forget to close the file after performing operations to make sure proper handling of system resources is attained.