File Handling in Python

In this tutorial, you'll learn file handling in Python, file operations such as opening a file, reading from it, writing into it, closing it, renaming a file, deleting a file, and various file methods.

To store data temporarily and permanently, we use files. A file is the collection of data stored on a disk in one unit identified by filename.

Types of File

• Text File: Text file usually we use to store character data. For example, test.txt
• Binary File: The binary files are used to store binary data such as images, video files, audio files, etc.

File Path

A file path defines the location of a file or folder in the computer system. There are two ways to specify a file path.

1. Absolute path: which always begins with the root folder
2. Relative path: which is relative to the program's current working directory

The absolute path includes the complete directory list required to locate the file.

For example, /user/Pynative/data/sales.txt is an absolute path to discover the sales.txt. All of the information needed to find the file is contained in the path string.

After the filename, the part with a period(.) is called the file's extension, and that tells us the type of file. Here, project.pdf is a pdf document.

Read File

To read or write a file, we need to open that file. For this purpose, Python provides a built-in function open().

Pass file path and access mode to the open(file_path, access_mode) function. It returns the file object. This object is used to read or write the file according to the access mode.

Accesss mode represents the purpose of opening the file. For example, R is for reading and W is for writing

In this article, we will use the test.txt file for manipulating all file operations. Create a text.txt on your machine and write the below content in it to get started with file handling.

Welcome to PYnative.com
This is a sample.txt
Line 3
Line 4
Line 5

Example:

# Opening the file with absolute path
fp = open(r'E:\demos\files\sample.txt', 'r')
# read file
print(fp.read())
# Closing the file after reading
fp.close()

# path if you using MacOs
# fp = open(r"/Users/myfiles/sample.txt", "r")

Output:

Welcome to PYnative.com
This is a sample.txt
Line 3
Line 4
Line 5

Read More:

• Create File in Python:
• Open a File in Python
• Read File in Python
• Read Specific Lines From a File in Python

Note:

When we open a file, the operating system gives a handle to read and write a file. Once we have done using the file, it is highly recommended to close it. Because a closed file reduces the risk of being unwarrantedly modified, it will also free up the resources tied with the file.

File Access Modes

The following table shows different access modes we can use while opening a file in Python.

Writing to a File

To write content into a file, Use the access mode w to open a file in a write mode.

Note:

• If a file already exists, it truncates the existing content and places the filehandle at the beginning of the file. A new file is created if the mentioned file doesn’t exist.
• If you want to add content at the end of the file, use the access mode a to open a file in append mode

Example

text = "This is new content"
# writing new content to the file
fp = open("write_demo.txt", 'w')
fp.write(text)
print('Done Writing')
fp.close()

Read More:

• Write to File in Python

Move File Pointer

The seek() method is used to change or move the file's handle position to the specified location. The cursor defines where the data has to be read or written in the file.

The position (index) of the first character in files is zero, just like the string index.

Example

f = open("sample.txt", "r")
# move to 11 character
f.seek(11)
# read from 11th character
print(f.read())

Output:

PYnative.com
This is a sample.txt
Line 3
Line 4
Line 5

The tell() method to return the current position of the file pointer from the beginning of the file.

tell() Example

f = open("sample.txt", "r")
# read first line
f.readline()
# get current position of file handle
print(f.tell())

# Output 25

Read More: Complete Guide on File Seek(): Move File Pointer Position

Python File Methods

Python has various method available that we can use with the file object. The following table shows file method.

Copy Files

There are several ways to cop files in Python. The shutil.copy() method is used to copy the source file's content to the destination file.

Example

import shutil

src_path = r"E:\demos\files\report\profit.txt"
dst_path = r"E:\demos\files\account\profit.txt"
shutil.copy(src_path, dst_path)
print('Copied')

Read More:

• Copy Files in Python
• Move Files in Python

Rename Files

In Python, the os module provides the functions for file processing operations such as renaming, deleting the file, etc. The os module enables interaction with the operating system.

The os module provides rename() method to rename the specified file name to the new name. The syntax of rename() method is shown below.

Example

import os

# Absolute path of a file
old_name = r"E:\demos\files\reports\details.txt"
new_name = r"E:\demos\files\reports\new_details.txt"

# Renaming the file
os.rename(old_name, new_name)

Read More:

• Rename Files in Python

Delete Files

In Python, the os module provides the remove() function to remove or delete file path.

import os

# remove file with absolute path
os.remove(r"E:\demos\files\sales_2.txt")

Read More:

• Delete Files and Directories in Python
• Delete Lines From a File in Python

Working With Bytes

A byte consists of 8 bits, and bits consist of either 0 or 1. A Byte can be interpreted in different ways like binary octal, octal, or hexadecimal. Python stores files in the form of bytes on the disk.

When we open a file in text mode, that file is decoded from bytes to a string object. when we open a file in the binary mode it returns contents as bytes object without decoding.

Now let's see the steps to write bytes to a file in Python.

• Open the file in binary write mode using wb
• Specify contents to write in the form of bytes.
• Use the write() function to write byte contents to a binary file.

Example

bytes_data = b'\x21'

with open("test.txt", "wb") as fp:
    # Write bytes to file
    fp.write(bytes_data)

Exercise:

Python Count Number of Lines in a File