Function to get the week number based on a given date_string

gist: date_to_week_number.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
__author__ = "[José M. Beltrán](<beltran.data@gmail.com>)"
__credits__ = ["José M. Beltrán"]
__license__ = "GPL-3.0"

def date_to_week_number(date_string):
    """
    :param date_string:  input a date_string with format YYYYmmdd
    :return: the week number for the given date_string
    """
    import datetime

    fmt = '%Y%m%d'  # YYYYmmdd format
    dt = datetime.datetime.strptime(str(date_string), fmt)
    # isocalendar Returns a 3-tuple, (ISO year, ISO week number, ISO weekday)
    # See https://docs.python.org/2/library/datetime.html
    wk = dt.isocalendar()[1]

    return wk