combine.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import csv


def make_dictionary(source_path):
    with open(source_path, encoding='utf-8') as fh:
        tuples = []
        for line in fh:
            tuples.append(line.strip().split('\t'))
        return dict(tuples)


def combine(fin_path, fout_path, code_dict):
    with open(fin_path, encoding='utf-8') as fin, \
         open(fout_path, mode='wt', encoding='utf-8', newline='') as fout:
        cin = csv.DictReader(fin, fieldnames=['UID', 'COIN', 'FREE_COIN'])
        cout = csv.DictWriter(fout, ['CODE', 'UID', 'COIN', 'FREE_COIN'])
        cout.writeheader()
        for row in cin:
            row['CODE'] = code_dict[row['UID']]
            cout.writerow(row)


def main():
    code_dict = make_dictionary('uid_map.txt')
    combine('source.csv', 'result.csv', code_dict)


if __name__ == "__main__":
    main()