Early Attempt at identifying fiscal week

fiscal_week.py

from datetime import datetime, timedelta
import pandas as pd

def get_fw(date, fiscal_start=datetime(1970, 1,1), calendar_day=False):
    """
    Obtain fiscal week from a datetime object.
    
    :fiscal_start: Indicate the start of a fiscal year
    :calendar_day: If False the first full week is Week 1.
    """
    if datetime(1970, date.month, date.day) > datetime(1970, fiscal_start.month, fiscal_start.day):
        offset = 1 if fiscal_start.isocalendar()[2] == 1 or calendar_day else 0
        week = date.isocalendar()[1] - fiscal_start.isocalendar()[1] + offset
    else:
        weeks_in_year = 53 if datetime(date.year, fiscal_start.month, fiscal_start.day).isocalendar()[2] > datetime(date.year - 1, fiscal_start.month, fiscal_start.day).isocalendar()[2] else 52
        offset = 0 if fiscal_start.isocalendar()[2] == 1 or calendar_day else 1
        week = weeks_in_year + (date.isocalendar()[1] - fiscal_start.isocalendar()[1]) + offset
    return (week, date.year - 1 if week == 53 else date.year)

def get_fw_string(*args, **kwargs):
    """
    A wrapper for get_fw. This provides the date in a human readable format.
    """
    date_tuple = get_fw(*args, **kwargs)
    return '{1} - Week {0}'.format(date_tuple[0], date_tuple[1])

def get_month(date):
    return (date.month, date.year)

def get_month_string(*args, **kwargs):
    month_tuple = get_month(*args, **kwargs)
    return '{} - {}'.format(month_tuple[1], month_tuple[0])