children.py

import random

def generate_pairs(n):
    return [(random.choice(["b","g"]), random.choice(["b","g"])) for i in range(n)]

def generate_children(n):
    return [random.choice(["b","g"]) for i in range(n)]

def flatten(alist):
    result = []
    for group in alist:
        result += group
    return result

# Scenario 1
# pick a pair, choose a child at random
# if it's not a boy, then this didn't happen (continue),
# otherwise check the other
count = 0
count_both = 0
pairs = generate_pairs(100000)
while count < 10000:
    pair = random.choice(pairs)
    choice = random.choice(pair)
    # if it's not a boy, this didn't happen
    if choice == 'b':
        count += 1
        if pair[0] == pair[1]:
            count_both += 1

print("Scenario 1:", count, count_both, count_both/count)

# scenario 2
# pick a pair with at least one boy. 
# If the oldest isn't a boy, this didn't happen
# check if they're both boys.
count = 0
count_both = 0
pairs = generate_pairs(100000)
while count < 10000:
    pair = random.choice(pairs)
    # eldest must be a boy
    if 'b' not in pair:
        continue
    if pair[1] != 'b':
       continue
    count += 1
    if pair[0] == pair[1]:
        count_both += 1

print("Scenario 2:", count, count_both, count_both/count)

# scenario 2.5
# pick a pair with at least one boy. If the youngest isn't a boy, this didn't happen
# check if they're both boys.
count = 0
count_both = 0
pairs = generate_pairs(100000)
while count < 10000:
    pair = random.choice(pairs)
    # eldest must be a boy
    if 'b' not in pair:
        continue
    if pair[0] != 'b':
       continue
    count += 1
    if pair[0] == pair[1]:
        count_both += 1

print("Scenario 2.5:", count, count_both, count_both/count)

# scenario 3
# pick a pair, if neither are boys, this didn't happen,
# then pick a child at random,
# if it's not a boy, then this didn't happen
# then check if both are boys
count = 0
count_both = 0
pairs = generate_pairs(100000)
while count < 10000:
    pair = random.choice(pairs)
    # filter to boys
    if 'b' not in pair:
       continue
    # pick a child at random
    choice = random.choice(list(enumerate(pair)))
    # if it's not a boy, this didn't happen
    if choice[1] == 'b':
        count += 1
        if pair[0] == pair[1]:
            count_both += 1

print("Scenario 3:", count, count_both, count_both/count)

# scenario 4
# pick a pair, if neither are boys, this didn't happen,
# and then check if they're the same
count = 0
count_both = 0
pairs = generate_pairs(100000)
while count < 10000:
    pair = random.choice(pairs)
    if 'b' not in pair:
       continue
    # count it and move on
    count += 1
    if pair[0] == pair[1]:
        count_both += 1

print("Scenario 4:", count, count_both, count_both/count)

# scenario 5
# pick a child, if it's not a boy, this didn't happen
# then check if the other child in the pair is the same
count = 0
count_both = 0
pairs = generate_pairs(100000)
children = flatten(pairs)
indexed_children = list(enumerate(children))
while count < 10000:
    # (index, gender)
    indexed_child = random.choice(indexed_children)
    if indexed_child[1] != 'b':
        continue
    count += 1
    index = indexed_child[0]
    if index % 2 == 0:
        if children[index] == children[index + 1]:
            count_both += 1
    else:
        if children[index] == children[index - 1]:
            count_both +=1   


print("Scenario 5:", count, count_both, count_both/count)

# scenario 6
# pick a pair, if neither are boys, this didn't happen
# except 25% of the time it does. Then check if they're
# the same.
count = 0
count_both = 0
pairs = generate_pairs(100000)
while count < 10000:
    pair = random.choice(pairs)
    if 'b' not in pair and random.uniform(0,1) > .25:
       continue
    # count it and move on
    count += 1
    if pair[0] == pair[1]:
        count_both += 1

print("Scenario 6:", count, count_both, count_both/count)