choices.py

#!/usr/bin/env python

# usage: choices choice_a 1 choice_b 5 choice_c 4
# will return choice_a 10% of the time, choice_b 50% of the time
# and choice_c 40% of the time

from random import randrange
import sys

options = []
total = 0

args = sys.argv[1:]
if args and len(args) % 2 == 0:
  while args:
    options.append((args[0], int(args[1])))
    total += int(args[1])
    args = args[2:]

n = randrange(0, total)
for option in options:
  n = n - option[1]
  if n < 0:
    print(option[0])
    break