#!/usr/bin/env python

# Concatenates spreadsheet columns in the order provided.

# The position and header of the combined column are that of the first column.

import csv

import sys

def main():

    try: _prog_name, col0_num, col1_num = sys.argv

    except ValueError: raise SystemExit('Usage: '+sys.argv[0]

        +' <in col0# col1# [| '+sys.argv[0]+' new_col0# new_col1#]... >out')

    col0_num, col1_num = map(int, [col0_num, col1_num])

    # Transform input

    reader = csv.reader(sys.stdin)

    writer = csv.writer(sys.stdout)

    is_header = True

    for row in reader:

        if is_header: is_header = False # don't concatenate headers

        else: row[col0_num] += row[col1_num]

        del row[col1_num]

        writer.writerow(row)

main()