高速文字列解析の世界 §2.5 符号

several_coding_examples.py

# -*- coding: utf-8 -*-

def unary(x):
    return "0" * (x - 1) + "1"

def binary(x):
    return bin(x)[2:]

def gamma(x):
    bx = binary(x)
    c1 = unary(len(bx))
    return c1 + bx[1:]

def delta(x):
    bx = binary(x)
    c1 = gamma(len(bx))
    return c1 + bx[1:]

def golomb(x, k=8):
    xp = x - 1
    r = (xp // k) + 1
    m = xp % k
    c1 = unary(r)
    c2 = binary(m)
    while len(c2) < len(binary(k - 1)):
        c2 = '0' + c2
    return c1 + c2

if __name__ == '__main__':
    lX = [1, 3, 5, 10, 100]
    for x in lX:
        unary_x = unary(x)
        binary_x = binary(x)

        print("x={}".format(x))
        # print("(x)₁={}".format(unary_x))
        print("(x)₂={}".format(binary_x))

        gamma_x = gamma(x)
        delta_x = delta(x)
        golomb_x = golomb(x)
        print("γ(x)={}".format(gamma_x))
        print("δ(x)={}".format(delta_x))
        print("G(x)={}".format(golomb_x))