How to Retrieve File Size in Python

Have you ever needed to retrieve the size of a file in Python? Perhaps you wanted to check if a particular file was too large to be processed, or maybe you needed to ensure that a file met certain size requirements before sending it over a network. Whatever the reason, retrieving the file size in Python is a straightforward process that can be accomplished with just a few lines of code. In this article, we’ll cover everything you need to know to retrieve file size in Python, including the different methods available and how to use them effectively.

Table of Contents

What is File Size?

Before we dive into the different ways to retrieve file size in Python, let’s take a moment to define what we mean by file size. File size refers to the amount of space a file takes up on a storage device, typically measured in bytes, kilobytes, megabytes, or gigabytes. The file size can provide useful information about a file, such as how long it will take to transfer over a network, how much storage space it will consume, and whether it meets certain size requirements.

Method 1: Using os.path.getsize()

The most common way to retrieve file size in Python is by using the os.path.getsize() function. This function returns the size of a file in bytes and takes the file path as an argument. Here is an example:

import os

file_path = "/path/to/file.txt"
file_size = os.path.getsize(file_path)

print(f"The size of {file_path} is {file_size} bytes.")

In this example, we imported the os module and used the os.path.getsize() function to retrieve the size of a file at the given file path. We then printed out a message that displays the file path and size in bytes. If you want to display the size in a different unit, you can perform some simple math to convert the bytes to the desired unit.

import os

file_path = "/path/to/file.txt"
file_size = os.path.getsize(file_path)
mb_size = file_size / (1024 * 1024)

print(f"The size of {file_path} is {mb_size:.2f} MB.")

In this example, we again used the os.path.getsize() function to retrieve the file size in bytes. We then divided the file size by 1024 twice to convert it from bytes to megabytes. Finally, we used f-strings to print out a message that displays the file path and size in megabytes, rounded to two decimal places.

Method 2: Using os.stat()

Another way to retrieve file size in Python is by using the os.stat() function. This function returns a tuple of file attributes, including the file size in bytes. Here is an example:

import os

file_path = "/path/to/file.txt"
file_stats = os.stat(file_path)

print(f"The size of {file_path} is {file_stats.st_size} bytes.")

In this example, we used the os.stat() function to retrieve a tuple of file attributes, including the file size in bytes. We then accessed the file size attribute using the st_size property and printed out a message that displays the file path and size in bytes.

Method 3: Using pathlib.Path()

If you prefer a more object-oriented approach, you can use the pathlib module to retrieve file size in Python. The Path class provides a method called stat() that returns a named tuple of file attributes, including the file size in bytes. Here is an example:

from pathlib import Path

file_path = Path("/path/to/file.txt")
file_stats = file_path.stat()

print(f"The size of {file_path} is {file_stats.st_size} bytes.")

In this example, we imported the Path class from the pathlib module and created a Path object for the file at the given file path. We then called the stat() method on the Path object to retrieve a named tuple of file attributes, including the file size in bytes. Finally, we printed out a message that displays the file path and size in bytes.

Handling Errors

When working with files in Python, it’s important to handle errors that may arise. For example, if the file path you provide does not exist or is not accessible, you may encounter an OSError. Here is an example of how to handle this error with a try-except block:

import os

file_path = "/path/to/file.txt"

try:
    file_size = os.path.getsize(file_path)
    print(f"The size of {file_path} is {file_size} bytes.")
except OSError as e:
    print(f"Error: {e}")

In this example, we used a try-except block to handle the OSError that may occur if the file path is invalid. We attempted to retrieve the file size with os.path.getsize() within the try block and printed out a message as before. If an OSError is raised, we caught it with the except block and printed out an error message instead.

Conclusion

Retrieving file size in Python is a useful task that can be accomplished with a few simple lines of code. In this article, we covered three different methods for retrieving file size in Python: using os.path.getsize(), using os.stat(), and using pathlib.Path(). We also discussed how to handle errors that may arise when working with files. Armed with this knowledge, you should be able to easily retrieve file size in your Python scripts and applications.

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