如何用Python将输入文本文件的指定列分别保存到独立输出文件

Got it, let's build exactly what you need step by step. Below is a complete septc.py script that handles your column extraction requirement, with explanations to help you follow along.

import argparse
from contextlib import ExitStack

def main():
    # Set up command-line argument parser
    parser = argparse.ArgumentParser(description='Pull specific columns from a text file into separate output files.')
    parser.add_argument('--infile', required=True, help='Path to your input text file')
    parser.add_argument('--column', required=True, nargs='+', type=int, help='0-based indices of columns to extract (e.g., 0 2 3)')
    parser.add_argument('--outfile', required=True, nargs='+', help='Output file paths (one for each column, in order)')
    
    args = parser.parse_args()
    
    # First, make sure column count matches output file count
    if len(args.column) != len(args.outfile):
        print("Error: Number of columns must match number of output files!")
        return
    
    # Use ExitStack to safely manage multiple output files
    with ExitStack() as stack:
        # Open all output files in write mode (auto-closes later)
        out_files = [stack.enter_context(open(fname, 'w')) for fname in args.outfile]
        
        # Process input file line by line (memory-friendly for large files)
        with open(args.infile, 'r') as infile:
            for line in infile:
                # Split line into columns (adjust delimiter if needed)
                columns = line.strip().split()
                # Write each selected column to its corresponding file
                for col_idx, out_file in zip(args.column, out_files):
                    # Handle lines with fewer columns than requested
                    if col_idx < len(columns):
                        out_file.write(f"{columns[col_idx]}\n")
                    else:
                        # Write empty line if column doesn't exist in this row
                        out_file.write("\n")

if __name__ == '__main__':
    main()

Key Details & Usage: #

• Argument Handling: The script uses Python's built-in argparse to parse your command-line inputs. The nargs='+' flag lets you pass multiple values for --column and --outfile.
• Validation: It first checks that the number of columns matches the number of output files—no more mismatched inputs!
• Safe File Management: ExitStack ensures all output files are closed properly, even if an error mid-execution.
• Line-by-Line Processing: Reads the input file one line at a time, which is efficient for large files that might crash your RAM if loaded entirely.

Run it exactly like your example:

python septc.py --infile infile.txt --column 0 2 3 --outfile out1.txt out2.txt out3.txt

Customization Tips: #

• Delimiter: If your file uses commas, tabs, or another separator instead of whitespace, replace split() with split(',') (or your delimiter of choice).
• Edge Case Adjustment: If you don't want empty lines for missing columns, you can replace the else block with pass to skip writing anything for those lines.

内容的提问来源于stack exchange，提问作者nic