Find most frequent numbers from a Twilio CSV export

twilio_csv_find_most_frequent_numbers.py

#!/usr/bin/python3

import csv
import operator
import sys


if len(sys.argv) < 2:
    print('need csv file as first arg')
    sys.exit(1)


numbers = {}  # numbers as keys, occurrences as values
no_of_sms = 0

# TODO(niklas9):  * create proper class etc for this
with open(sys.argv[1], 'r', encoding='utf-8') as f:
    reader = csv.reader(f)
    for row in reader:
        # TODO(niklas9):
        #  * should filter out header row if it exists
        #  * to increase perf for larger csv files, could split in
        #    n threads here where each thread works on part of the file, then
        #    merge the results
        if not len(row) > 1:  continue  # some lines might be blank
        number = row[1]
        if number in numbers:
            numbers[number] += 1
        else:
            numbers[number] = 1
        no_of_sms += 1

# TODO(niklas9):
# * actually just looking for the top ~5 numbers here, instead of sorting this
#   could be done in O(n*size) runtime complexity instead, where size=5 in this
#   example.. only beneficial though if size < log(n), using the same numbers if
#   n>149 (as e^5=148.31..)
numbers_sorted = sorted(numbers.items(), key=operator.itemgetter(1),
                        reverse=True)
print('unique numbers = {:d}'.format(len(numbers_sorted)))
print('sms sent = {:d}\n'.format(no_of_sms))


for item in numbers_sorted[:5]:  # print top 5
    print(item)