How to open multiple files using “with open” in Python

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Welcome to akashITS (Akash IT Solutions), In this article, you will learn about: How to open multiple files using “with open” in Python

How to open multiple files using “with open” in Python

Python provides some very convenient ways to work with file-like objects, including the with feature.

The with open statement is a frequently used tool in Python for opening files. Even in the event that an exception is raised, it makes sure the file is correctly closed when the suite is finished. Use multiple with open statements if you wish to open numerous files at once.

Below are some examples

Opening Multiple Files:

file_paths = ['file_1.txt', 'file_2.txt', 'file_3.txt']

# Open multiple files using a loop
with [open(file_path, 'r') for file_path in file_paths] as files:
    for file in files:
        content = file.read()
        # Do something with the content
# Files are automatically closed after exiting the 'with' block

Writing to Multiple Files:

result_files = ['result1.txt', 'result2.txt', 'result3.txt']

# Open multiple files for writing
with [open(result_file, 'w') for result_file in result_files] as files:
    for file in files:
        file.write("Hello, python!\n")
        # You can write any content to the files

# Files are automatically closed after exiting the 'with' block

Reading and Writing Simultaneously:

input_files = ['input1.txt', 'input2.txt']
output_files = ['output1.txt', 'output2.txt']

# Open multiple files for reading and writing
with [open(input_file, 'r') for input_file in input_files] as inputs, \
        [open(output_file, 'w') for output_file in output_files] as outputs:
    for input_file, output_file in zip(inputs, outputs):
        content = input_file.read()
        # Process content if needed
        output_file.write("Completed: " + content)

# Files are automatically closed after exiting the 'with' block

Please note that the above examples, the with statement is used with a list comprehension to create a list of file objects. The with block ensures that each file is properly closed after the block is executed.

Using ‘with open’ in a Loop:

Another way to open multiple files is to just use a loop and open each file one at a time so that no two files are open simultaneously. This can be helpful if you’re working with very large files and can’t have multiple files open due to memory constraints.

filenames = ['file1.txt', 'file2.txt', 'file3.txt']
for file in filenames:
    with open(file, 'r') as f:
        print(f.read())

Here, we loop over our list of filenames. For each one, we use with open to open the file and assign it to the variable f. We then print out the contents of the file. Once the with block is exited, the file is automatically closed.

Errors Handling while Opening Multiple Files Using with:

When working with files in any programming language, it’s common to have to handle errors since so much can go wrong. Python’s with keyword and try/except blocks can work together to better handle these errors.

For Examples

filenames = ["file1.txt", "file2.txt", "nonexistent.txt", "file3.txt"]
for name in filenames:
    try:
        with open(name, 'r') as f:
            print(f.read())
    except FileNotFoundError:
        print(f"{name} not found.")
    except PermissionError:
        print(f"You don't have permission to read {name}.")

In this example, we attempt to open four files with a loop. We’ve wrapped the file opening operation inside a with block which is itself enclosed in a try/except block. This way, if the file doesn’t exist, a FileNotFoundError is caught and a custom error message is printed. We use it this way to specifically handle certain scenarios and letting with handle the closing of the file, if it was ever opened. You can adjust the file paths, modes (‘r’ for reading, ‘w’ for writing, ‘a’ for appending, etc.), and content handling according to your specific needs.

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