gzip folder python with code examples

If you've ever worked with large files, you know how important it is to compress them. Compressed files take up less space on your hard drive and can be transferred more quickly over the internet. One way to compress files in Python is to use the gzip module. This module provides a simple way to compress and decompress files or folders in the .gz format.

In this article, we will cover what the gzip module is, how it works, and how you can use it to compress and decompress files or folders in Python, along with some code examples.

What is the gzip module?

The gzip module in Python provides a way to compress and decompress files or folders in the GZIP file format, which is a widely used open-source data compression program. The program was created by Jean-loup Gailly and Mark Adler, and its name comes from the fact that it primarily uses the GNU zip file format (.gz).

How does the gzip module work?

The gzip module allows you to compress and decompress files or folders in Python by providing functions for opening, reading, writing, and closing gzip files. It operates on 'gzip' files, which are pretty simply glorified sequences of compressed chunks of data. The module provides an interface to deal with the compressed data as highly compressed byte streams.

To use the gzip module, you need first to import it into your script using the import statement. The gzip module provides two classes: GzipFile and BytesIO.

GzipFile: This class provides a compression and decompression interface for files that can be read and written. You can use it to create a gzip file and write compressed data to it, or you can use it to read data from a .gz file and decompress it.

BytesIO: This class provides an in-memory byte buffer interface that can be used for compressing and decompressing data. It's similar to the GzipFile class, but instead of reading and writing to a file, you can read and write to an in-memory buffer.

The gzip module provides several functions for compressing and decompressing data. Here are some of the essential ones:

1. open(): This function opens a gzip file for reading or writing. You can use it to create a new gzip file or open an existing one.

2. read(): This function reads compressed data from a gzip file.

3. write(): This function writes compressed data to a gzip file.

4. close(): This function closes an open gzip file.

How to use the gzip module in Python?

Let’s look at four examples that demonstrate some common uses of the gzip module.

1. Compressing a File Using gzip Module

The code below shows how to compress a file using the gzip module:

import gzip
with open('filename.txt', 'rb') as f_in:
    with gzip.open('compressed_filename.txt.gz', 'wb') as f_out:
        f_out.writelines(f_in)

The function takes two arguments: the input file name and the output file name. In this example, 'filename.txt' is the input file name, and 'compressed_filename.txt.gz' is the output file name.

The open method is used to create a file object in reading mode. The gzip.open method is used to create a file object in writing compressed mode. The data is then passed to f_out using the writelines method.

2. Decompressing a File Using gzip Module

The code below shows how to decompress a file using the gzip module:

import gzip
with gzip.open('compressed_filename.txt.gz', 'rb') as f_in:
    with open('decompressed_filename.txt', 'wb') as f_out:
        f_out.writelines(f_in)

The function takes two arguments: the input file name and the output file name. In this example, 'compressed_filename.txt.gz' is the input file name, and 'decompressed_filename.txt' is the output file name.

The gzip.open method is used to create a file object in reading compressed mode. The open method is used to create a file object in writing mode. The data is then passed to f_out using the writelines method.

3. Compressing Multiple Files into One Archive

The code below shows how to compress multiple files into one archive using the gzip module:

import gzip
import os

def compress_multiple_files_to_archive(folder_path, archive_name):
    with gzip.open(archive_name, 'wb') as f_out:
        for filename in os.listdir(folder_path):
            file_path = os.path.join(folder_path, filename)
            with open(file_path, 'rb') as f_in:
                f_out.write(f_in.read())
    print("Files have been compressed into {}".format(archive_name))

folder_path = 'path/to/folder'
archive_name = 'archive.gz'
compress_multiple_files_to_archive(folder_path, archive_name)

The function compresses all the files present in the folder into one archive file named archive.gz. In the first line of the function, we are creating a gzip file object and specifying its name. We then loop through all the files in the specified folder using the os.listdir method.

For each file, we open it in the binary mode rb to read the contents and pass it to the file object using the write method which writes data to the archive in compressed form.

4. Extracting Multiple Files from Archive

The code below shows how to extract multiple files from the archive into a folder using the gzip module:

import gzip
import os

def extract_files_from_archive(archive_name, folder_path):
    with gzip.open(archive_name, 'rb') as f_in:
        with open('archive_temp.txt', 'wb') as f_out:
            f_out.write(f_in.read())
    with open('archive_temp.txt', 'r') as f:
        filenames = f.readlines()
        for filename in filenames:
            with gzip.open(filename.strip(), 'rb') as f_in:
                with open(os.path.join(folder_path, os.path.basename(filename.strip())[:-3]), 'wb') as f_out:
                    f_out.writelines(f_in)
    os.remove('archive_temp.txt')
    print('Files have been extracted from {}'.format(archive_name))

archive_name = 'path/to/archive.gz'
folder_path = 'path/to/folder'
extract_files_from_archive(archive_name, folder_path)

The function extracts all the files present in the archive into the specified folder. The first step is to read the contents of the archive into a temporary file named archive_temp.txt using the gzip module.

We then read the filenames from the temporary file and loop through them. For each filename, we write the compressed contents of the file to a destination file in the folder specified.

At the end of the function, we remove the temporary file, and the function returns the statement 'Files have been extracted from {}'.format(archive_name)'.

Conclusion

The gzip module is a powerful tool that provides a simple way to compress and decompress files in Python. In this article, we've covered some of the basics, such as what the gzip module is, how it works, and how to use it to compress and decompress files or folders in Python, along with some code examples. The examples above should give you a kick-start to using the gzip module in your Python applications.

Alright, let's dive a bit deeper into some of the previous topics we covered in the article.

1. GzipFile vs BytesIO

As mentioned earlier, the gzip module provides two classes: GzipFile and BytesIO. While both classes can be used to compress and decompress data, there are some differences between them that you should be aware of.

GzipFile – This class is used to operate on files, so you would use it when you want to read from or write to a gzip file. For example, if you want to compress a large file, you can use the GzipFile class to write the compressed data to a new gzip file.

BytesIO – This class is used to store data in memory, so you would use it when you want to compress or decompress data that is not in a file. For example, if you want to compress a string or a Python object, you can use the BytesIO class to write the compressed data to an in-memory buffer.

2. Handling Large Files

One issue you may encounter when working with the gzip module is handling large files. In some situations, a file may be too large to fit into memory, causing your Python program to crash. If you're working with large files, you may want to consider using the GzipFile class in combination with the read(), write(), and flush() methods.

The read() method can be used to read a certain number of bytes from a gzip file into a buffer, without loading the entire file into memory. Similarly, the write() method can be used to write a certain number of bytes to a gzip file. Finally, the flush() method can be used to write any remaining data to the file.

By using these methods in combination, you can read and write large files in smaller chunks, without overwhelming your system's memory.

3. Compression Level

One important thing to keep in mind when using the gzip module is that you can specify the compression level when compressing data. The compression level can have a significant impact on the size of the compressed file, as well as the amount of time it takes to compress and decompress the file.

The compression level is specified as an integer between 1 and 9, with 1 being the fastest but least compression and 9 being the slowest but most compression. The default compression level is 9.

To specify the compression level, you can pass a second argument to the gzip.open() function. For example:

import gzip

with open('input.txt', 'rb') as f_in:
    with gzip.open('output.gz', 'wb', compresslevel=6) as f_out:
        f_out.writelines(f_in)

In this example, the compresslevel argument is set to 6, which provides a good balance between compression and speed.

4. Error Handling

Finally, it's important to properly handle errors when working with the gzip module. Some common errors you may encounter include:

• FileNotFoundError: Occurs when the specified input file or output file cannot be found.
• IOError: Occurs when there is an issue with reading or writing to a file.
• EOFError: Occurs when the end of a gzip file is reached unexpectedly.

To handle errors, you can use try-except blocks around your code. For example:

import gzip

try:
    with open('input.txt', 'rb') as f_in:
        with gzip.open('output.gz', 'wb') as f_out:
            f_out.writelines(f_in)
except FileNotFoundError:
    print('Input file not found.')
except IOError:
    print('There was an error reading or writing the files.')
except EOFError:
    print('End of file reached unexpectedly.')

By handling errors in this way, you can ensure that your program doesn't crash if there is an issue with reading or writing files.

Overall, the gzip module is a powerful and flexible tool that can be used to compress and decompress files and data in Python. By understanding the GzipFile and BytesIO classes, handling large files, specifying compression levels, and properly handling errors, you can effectively use the gzip module in your Python projects.

Popular questions

1. What is the gzip module used for in Python?

• The gzip module in Python is used for compressing and decompressing files or folders in the GZIP file format.

2. What are the two classes provided by the gzip module?

• The gzip module provides two classes: GzipFile and BytesIO.

3. How can you compress a single file using the gzip module in Python?

• You can compress a single file using the gzip module in Python by opening the file, creating a new gzip file object with the gzip.open() function, and then using the write() method to write compressed data to the new file.

4. How can you compress multiple files into one archive using the gzip module in Python?

• You can compress multiple files into one archive using the gzip module in Python by looping through the files, reading each file into a buffer, and then writing the buffer to a new gzip file object.

5. How can you extract multiple files from an archive using the gzip module in Python?

• You can extract multiple files from an archive using the gzip module in Python by reading the archive into a temporary file, reading the filenames from the temporary file, and then looping through each filename, writing the compressed data to a new file.

Tag

"Compression"