Output the intersection of elements contained within the first column of the CSV files passed in as command line arguments.

union_csv.py

"""
Output the intersection of elements contained within the first column of the
passed-in CSV files.

Copyright 2012 Kevin Richardson

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE
"""
import csv
import sys


compare_list = []

for arg in sys.argv:
    if not arg.endswith('.csv'):
        continue

    with open(arg, 'Ur') as csv_file:
        temp_list = []
        reader = csv.reader(csv_file)
        for line in reader:
            temp_list.append(line[0].strip())
        compare_list.append(set(temp_list))

print set(compare_list[0]).intersection(*compare_list)