entropy 計算

entropy.py

import numpy as np
import sys

def _str2ep(s):
    done = set()
    l = len(s)
    arr = []
    for i in s:
        if not i in done:
            x = s.count(i)
            arr.append(x/l)
            done.add(i)
    return arr

def entropy(s):
    arr = _str2ep(s)
    return -(arr * np.ma.log(arr)).sum()

s = sys.argv[1]
print(entropy(s))