How can I run a script on multiple input files using Python?

To run a Python script on multiple input files, you can use a combination of file handling and looping. Here's a detailed approach with explanations:

1. Import Necessary Modules:

Begin by importing the os module, which is essential for interacting with the operating system, especially when listing files in a directory. You might also need other modules depending on what your script does (e.g., csv, json etc.)

2. Define the Directory and File Pattern (Optional):

If your input files are in a specific directory, define the directory path. You can also define a file pattern using modules like glob if you have files matching a certain naming convention (like .txt or data_.csv).

3. Loop through the files:

Use a loop to iterate through each file. Inside the loop, you'll perform your file processing actions.

4. Process each file:

Inside the loop, you will open the file and perform the necessary operations on its content. These operations will be specific to the functionality of your script.

5. Example Script:

Here's a comprehensive example that demonstrates how to apply a Python script to multiple text files:

import os

def process_file(file_path):
  try:
    with open(file_path, 'r') as file:
      # Process each line of the file, for example:
      for line in file:
        print(f"Processing line from {file_path}: {line.strip()}")

  except Exception as e:
    print(f"Error processing {file_path}: {e}")

def process_multiple_files(directory):
  for filename in os.listdir(directory):
    if filename.endswith(".txt"): # Filter files if needed
      file_path = os.path.join(directory, filename)
      process_file(file_path)

if __name__ == "__main__":
  input_directory = "input_files" # Create directory with multiple txt files called input_files
  if not os.path.exists(input_directory):
    print(f"Error: Directory '{input_directory}' does not exist.")
  else:
    process_multiple_files(input_directory)


6. Explanation:

- The script defines a function, process_file, which does the actual file processing and also has an error handling part.

- The function, process_multiple_files iterates over every item in directory, and checks if it is a text file, then calls the file processing function.

- The if __name__ == "__main__": ensures that the file processing function is called only when the script is executed.

7. Run the script:

Place this script in the same directory as your input files, or adjust the input_directory variable as required. This script will go over every file in a directory called input_files and print out each line in every txt file in the directory.

This provides a flexible way to run your python script over multiple input files. Remember to adjust the code to suit your specific file formats and processing requirements.

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