At CCHS hackerspace we make a lot of group parts orders to save shipping costs. This script can split up a a DigiKey order's total by participant (assuming each person's name is listed in the Customer Reference field for the order.)

digikey_ordersplit.py

#!/usr/bin/env python3
"""
Digikey order splitter script for group buys. For Python 3.x. Public Domain.

Supports cases where people are paying in a different currency to the Digikey currency,
and also pro rata splitting of shipping costs.

If you use this then please sanity check the results before sending them

Usage:
* Go to Digikey "My Digikey" -> "Web Order History" -> find the order (must be Submitted)
* Select "Download Order" -> "CSV w/ Header"
* Run script as:
  digikey_ordersplit.py <order CSV file> [optional total amount]

Names of people in the order must have been used to fill the "Customer
Reference" field. Only the first word (up to a space) is used for the
name, which allows you to also add item-specific comments
(designators, etc.) in the field if necessary.

The optional argument "total amount" is for if people are paying in a
different currency to the Digikey order currency. All amounts are
adjusted pro rata to meet the new total.

If the order includes a shipping charge then this is split up pro rata
between the order participants.

Uses floating point math everywhere because lazy.

TODO: Support the situation where multiple people order the same thing.

"""
import sys, csv, re

def main():
    if len(sys.argv) < 2 or len(sys.argv)> 3:
        print("Usage: digikey_ordersplit <order CSV file w/ header> [optional total amount]")
        return
    with open(sys.argv[1], 'r') as orderfile:
        reader = csv.reader(orderfile)
        # Skip the general order details to the "Index" subheader above the specifics
        for row in reader:
            if len(row) > 0 and row[0] == "Index":
                break
        participants = split_order(reader)
        shipping = find_shipping(reader)
        apply_pro_rata_shipping(participants, shipping)
        if len(sys.argv) == 3:
            scale_order(participants, float(sys.argv[2]))
        for name in participants:
            print("%s:" % name)
            for item in participants[name]:
                print("  {:2} {:<25} {:<40} - {:>5.2f}".format(*item))
            print("Total Share: {:>66.2f}\n".format(person_total(participants, name)))

    print("Order total (check against invoice): {:.2f}".format(order_total(participants)))

def split_order(csv):
    """ Split an order into a list of order items for each participant
    Items are tuples (qty, code, item, total price)
    """
    participants = {}
    for row in csv:
        if row[0] == "":
            return participants # have reached subtotal row
        name = row[4].title().split(" ")[0]
        if not name in participants:
            participants[name] = []
        qty = int(row[1])
        price = parse_price(row[8])
        participants[name].append((qty,row[2],row[3],price))
    return participants # should never get here but might if the CSV is the non-header kind

def find_shipping(csv):
    """ Find the Shipping line and return the shipping total """
    for row in csv:
        if len(row) > 7 and row[6] == "Shipping":
            return parse_price(row[7])
    return 0.0

def apply_pro_rata_shipping(participants, shipping):
    """ Apply a pro rata shipping charge to each participant, add it to their
    list of items"""
    if shipping == 0:
        return
    subtotal = order_total(participants)
    shipping = shipping
    for name in participants:
        share = person_total(participants, name) / subtotal * shipping
        participants[name].append((1,"","Share of Shipping",share))

def scale_order(participants, actual_total):
    """ Scale everything in the order so the order total reaches actual_total """
    old_total = order_total(participants)
    for name in participants:
        items = participants[name]
        participants[name] = [(qty,part,desc,cost/old_total*actual_total)
                              for (qty,part,desc,cost) in items]

def person_total(participants, name):
    """ Return the total for a given person's share of the order """
    return sum([p[3] for p in participants[name]])

def order_total(participants):
    """ Return the total for the order as given across all participants """
    return sum([person_total(participants, name) for name in participants])

def parse_price(price):
    """ Given a price of the form AU$0.40 (or similar), return a float """
    price = re.search(r"[\d\.]+$", price).group(0)
    return float(price)


if __name__ == "__main__":
    main()