how to run a script on multiple input files python,How to Run a Script on Multiple Input Files in Python

How to Run a Script on Multiple Input Files in Python

Running a script on multiple input files can be a time-consuming task, especially when dealing with a large number of files. However, with Python, you can automate this process and save yourself a significant amount of time. In this article, I will guide you through the steps to run a script on multiple input files, covering various aspects such as file naming conventions, script structure, and command-line arguments.

Understanding File Naming Conventions

Before you start writing your script, it’s essential to understand the file naming conventions of your input files. This will help you identify and process the files correctly. For instance, if your input files are named in a specific pattern, such as “input_data_001.txt”, “input_data_002.txt”, and so on, you can use this pattern to loop through the files in your script.

Here’s an example of how you can use a pattern to loop through files:

for i in range(1, 11):    file_name = f"input_data_{i:03}.txt"     Process the file

In this example, we use a for loop to iterate through the numbers 1 to 10 and construct the file name using an f-string. The format specifier “{i:03}” ensures that the number is zero-padded to three digits, which is useful for maintaining a consistent file naming convention.

Script Structure

When writing a script to process multiple input files, it’s crucial to structure your code in a way that is both readable and maintainable. Here’s a basic structure you can follow:

def process_file(file_name):     Process the file    passdef main():    for file_name in get_file_names():        process_file(file_name)if __name__ == "__main__":    main()

In this structure, we define a function called `process_file` that handles the processing of each file. This function can be as simple or as complex as needed, depending on the task at hand. The `main` function is responsible for looping through the files and calling the `process_file` function for each one. Finally, we check if the script is being run directly (not imported as a module) and call the `main` function if so.

Using Command-Line Arguments

One of the most convenient ways to run a script on multiple input files is by using command-line arguments. This allows you to specify the input files when running the script, making it easy to process different sets of files without modifying the script itself.

Here’s an example of how you can use command-line arguments in your script:

import sysdef process_file(file_name):     Process the file    passdef main():    for file_name in sys.argv[1:]:        process_file(file_name)if __name__ == "__main__":    main()

In this example, we use the `sys.argv` list to access the command-line arguments passed to the script. The first element of `sys.argv` is always the script name itself, so we start iterating from the second element (`sys.argv[1:]`). This allows us to pass the input file names as additional arguments when running the script.

Handling Different File Types

When processing multiple input files, it’s common to encounter different file types. To handle this, you can modify your script to check the file extension and apply different processing logic based on the file type.

Here’s an example of how you can handle different file types:

def process_text_file(file_name):     Process text file    passdef process_image_file(file_name):     Process image file    passdef process_file(file_name):    if file_name.endswith(".txt"):        process_text_file(file_name)    elif file_name.endswith(".jpg") or file_name.endswith(".png"):        process_image_file(file_name)    else:        print(f"Unsupported file type: {file_name}")def main():    for file_name in sys.argv[1:]:        process_file(file_name)if __name__ == "__main__":    main()

In this example, we define two separate functions, `process_text_file` and `process_image_file`, to handle text and image files, respectively. The `process_file` function checks the file extension and calls the appropriate function based on the file type. If the file type is unsupported, it prints a message to the console.