How to divide a number value in N unevenly parts using Python & following a set of min- & max requirement?

Question

I have a fairly basic math problem in Python & I dont know where to look.

Explanation:

• I have 100 dollars.
• I have 10 friends.
• I want to unevenly distribute my money across my friends.
• I want to this over & over again using a algorithm.

My only requirements are the following:

• The smallest amount any friend can receive should be > $5.
• The biggest amount any friend can receive should be < $40.

---

from random import randint, shuffle

def divide_number(number, parts_number, allow_zero = False ):

    if (parts_number > number):
        raise ValueError("Number of parts can't be higher than the number");

    parts = {currency: []}
    number_rest = number

    for i in range(1, parts_number + 1):
        if (i == parts_number):
            parts[currency].append(number_rest)
            break
        else:
            new_number = randint(0, number_rest) if allow_zero else randint(1, (number_rest - 
(parts_number - i)) // 2)

        number_rest -= new_number
        parts[currency].append(new_number)

    return parts

---

Running the function:

divide_number(100, 10)

Output

[2, 37, 8, 10, 2, 4, 4, 4, 26, 3]

---

This piece of code I've found online seems to work just great but it doesn't meet my requirements. How do I alter it so it does meet my requirements regarding min and max values?

So basicly, I want to go from unfair distribution to fair distribution.

Answer 1

Is is not easy to make rather fair distribution with limits. For reasonable sum and parts (p) values we can make p cells (friend pockets) and randomly put coin by coin into them (if possible)

import random

def randparts(summ, p, minn, maxx):
    maxx = maxx - minn
    summ -= p * minn
    if summ < 0:
        return None
    if p * maxx  >=  summ * 2:
        lst = [0] * p
        while summ > 0:
            r = random.randrange(p)
            if lst[r] < maxx:
                summ -= 1
                lst[r] += 1
    else:
        lst = [maxx] * p
        summ = maxx * p - summ
        while summ > 0:
            r = random.randrange(p)
            if lst[r] > 0:
                summ -= 1
                lst[r] -= 1
    for i in range(len(lst)):
        lst[i] += minn
    return lst

print(randparts(100, 10, 5, 40))

>>>[7, 17, 8, 10, 8, 8, 9, 12, 10, 11]

More concise and pythonic version from the comment of Olvin Roght (also removed the second branch for optimization for large summ values)

def randparts(number, divider, min_value, max_value):
    sum_min = divider * min_value
    if sum_min > number:
        return

    number -= sum_min
    result = [min_value] * divider
    while number:
        pocket = randrange(divider)
        if result[pocket] <= max_value:
            result[pocket] += 1
            number -= 1

    return result