Mix lists with a given ratio

mix_with_ratio.py

# inspired by https://stackoverflow.com/questions/10644925/randomly-interleave-2-arrays-in-python

def mix_with_ratio(a, b, ratio):
    c = []
    while a and b:
        which_list = random.random()
        if which_list < ratio:
            c.append(a.pop(0))
        else:
            c.append(b.pop(0))
    return c

# 10% chance of mixing b into a
mix_with_ratio(['a' for x in range(10)], ['b' for x in range(10)], 0.90)