# -*- coding: utf-8 -*-
num=0
file_name = 'origin'
file_ext = '.csv'

first_line = True
files = {}
file_idx = 0

with open(file_name+file_ext, 'r') as f:
    for line in f.readlines():
        if first_line == True:
            first_line = line
            continue
        key=line.split(",")[num]
        if key not in files:
            file_idx+=1
            target = open(file_name + str(file_idx) + file_ext,'w')
            target.write(first_line)
            target.write(line)
            files[key] = target
        else:
            target = files.get(key)
            target.write(line)
    for f in files:
        files.get(f).close()