Simple script implementing nchain benford's law distribution example

benford_intevals.py

# https://nchain.com/2019/10/22/benfords-wallet/

from collections import defaultdict
import random

def f(v, n):
    l = []
    for i in range(n-1):
        l.append(random.randint(1, v))
    l.append(v)
    return l


def g(l_in):
    l = sorted(l_in)
    last_value = 0
    l_out = []
    for current_value in l:
        interval = current_value - last_value
        l_out.append(interval)
        last_value = current_value
    return l_out

def count_leading_digits(l_in):
    d = defaultdict(int)
    for value in l_in:
        digit = int(str(value)[0])
        d[digit] += 1
    digit_counts = list(d.items())
    digit_counts.sort(key=lambda v: -v[1])
    return digit_counts


# Sample run in interpreter:
#  
# >>> l_g = f(45110034324222, 10000)
# >>> g_g = g(l_g)
# >>> count_leading_digits(g_g)
# [(1, 2888), (2, 1538), (3, 1277), (4, 1008), (5, 922), (6, 729), (7, 649), (8, 533), (9, 456)]
#

# Expected distribution:
# [   1,    2,    3,   4,   5,   6,   7,   8,   9]
# [30.1, 17.6, 12.5, 9.7, 7.9, 6.7, 5.8, 5.1, 4.6]