Date parameterization - Python vs Bash

parameterize.py

from datetime import date, datetime
from dateutil.relativedelta import relativedelta
from six import print_

exchanges = {
    'bitfinex': 'btcusd',
    'bitstamp': 'btcusd',
    'okcoin':   'btccny',
}

for exchange, asset in exchanges.items():
    dt = date(2015, 1, 1)
    today = datetime.utcnow().date()
    while (dt <= today):
        print_(exchange, asset, dt.year, dt.month) 
        dt += relativedelta(months=1)

parameterize.sh

#!/usr/bin/env bash

get_year_and_month() {
    echo $(date --date=$1 +"%Y %m")
}

add_month() {
    echo $(date --date="$1 + 1 month" +%Y-%m-%d)
}

startdate=2015-01-01
enddate=2016-01-01

for exchange in "bitfinex btcusd" "bitstamp btcusd" "okcoin btccny"; do
    date="$startdate"
    while [ $date != $(add_month $enddate) ]; do
        echo "$exchange" $(get_year_and_month $date)
        date=$(add_month $date)
    done
done

Python wins!