radix sort, improved from https://gist.github.com/rizkyabdilah/1740053

radix_sort.py

# based off of https://gist.github.com/rizkyabdilah/1740053 ;    resolved the case radix_sort([10000, 1000, 100, 10, 0])

def radix_sort(random_list):
    '''
      LSD (Least Significant Digit)
      I think this works only on positive integers
    '''
    max_num_digs=-float('inf') #  make sure we get to the max 10s place  of the numbers within "random_list"
    for e in random_list:
        if e==0: # was giving -inf when we took log(0)
            n_digs=1
        else:
            n_digs=int(np.floor(np.log10(e))) + 1
        if n_digs > max_num_digs:
            max_num_digs=n_digs

    len_random_list = len(random_list)
    modulus = 10
    div = 1
    while True:
        # empty array, [[] for i in range(10)]
        n_digits=10 # "10" b/c we're using decimal (for hex, it would be 16, etc.)
        new_list = [[] for i in range(n_digits)]
        # queue-based implementation
        for value in random_list:
            least_digit = value % modulus
            least_digit /= div
            new_list[least_digit].append(value)
        modulus = modulus * 10
        div = div * 10

        if len(new_list[0]) == len_random_list and div==10**(max_num_digs+1):
            return new_list[0]

        random_list = []
        for x in new_list:
            for y in x:
                random_list.append(y)