merge csv files into a single csv file with a column for the filename

merge.py

import sys
import glob
import os.path
import os
import argparse
import csv

def usage(args):
    parser = argparse.ArgumentParser()
    parser.add_argument("--delim", "-d", default="|")
    parser.add_argument("--skip", "-s", default=0, type=int)
    parser.add_argument("prefix")

    return parser.parse_args(args)

def fixup_row(row, filename):
    data = list(row)
    data.insert(0, os.path.splitext(filename)[0])

    return data

def add_file(skip_lines, reader, writer, filename, write_header):
    header_read = False
    for row in reader:
    	if skip_lines > 0:
    	    skip_lines -= 1
    	    continue
        if not header_read:
            if write_header:
                row = fixup_row(row, "run")
                writer.writerow(row)
                write_header = False
            header_read = True
        else:
            row = fixup_row(row, filename)
            writer.writerow(row)

    return not write_header

def main(args=sys.argv[1:]):
    args = usage(args)

    output_filename = "combined-{0}.csv".format(args.prefix)
    with open(output_filename, "wb") as out:
        writer = csv.writer(out)
        header_written = False
        for filename in glob.glob("{0}*.csv".format(args.prefix)):
            with open(filename, "rb") as inp:
                reader = csv.reader(inp, delimiter=args.delim)
                header_written = add_file(args.skip, reader, writer, filename, not header_written)

if __name__ == "__main__":
    main()