bounded zipf distribution-truncated Zipf distribution

zipf分佈的python實現，參考了[1],[2]。[2]是一個在NDN網絡中關於cache的一個仿真器。
 code:

import numpy as np
import random
import matplotlib.pyplot as plt
N = 7
x = np.arange(1, N+1)
alpha=1.1
pdf=x**(-alpha)
pdf/=pdf.sum()
cdf=np.cumsum(pdf)
sample=np.zeros((N,), dtype=np.int)
points=10000
for i in range(points):
    rv = random.random()
    axis=int(np.searchsorted(cdf, rv) + 1)
    sample[axis-1]+=1
print sample

 results:

[4170 1928 1285  888  734  510  485]

 The results conform with [1].

[1] Sampling from a bounded domain zipf distribution
[2] icarus-sim/icarus
[3] Zipf齊夫分佈及Java實現