Analyze item counts in CSV columns

analyze_csv.py

from collections import Counter
from argparse import ArgumentParser, FileType
from csv import DictReader, DictWriter
from sys import stdout

parser = ArgumentParser()
parser.add_argument("infile", type=FileType("r", encoding="utf-8"))
parser.add_argument("column_name")
parser.add_argument("-o", "--outfile", type=FileType("w", encoding="utf-8"), default=stdout)
args = parser.parse_args()
f_in = args.infile
f_out = args.outfile
column_name = args.column_name

reader = DictReader(f_in)
records = Counter(row[column_name] for row in reader)

writer = DictWriter(f_out, fieldnames=["record", "count"], delimiter="\t")
writer.writeheader()

for record, count in records.most_common():
    writer.writerow({"record": record, "count": count})