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发帖数: 273 | 1 【 以下文字转载自 Statistics 讨论区 】
发信人: myregmit (myregmit), 信区: Statistics
标 题: long time generating gamma distribution in python
发信站: BBS 未名空间站 (Thu Mar 13 19:04:24 2014, 美东)
I need to generate a truncated gamma distribution pdf curve and histogram in
python 3.
2 on win7.
import numpy as np
import matplotlib.pyplot as plt
import scipy.special as sps
shape, scale = 2., 2. # mean and dispersion
counter =0
s = []
upper_bound = 4
lower_bound = 0.5
while (counter <= 1000):
t = np.random.gamma(shape, scale, 1)
if (lower_bound <= t <= upper_bound) :
s.append(t)
counter += 1
count, bins, ignored = plt.hist(s, 50, normed=True)
// this part take s very long time
y = bins**(shape-1)*(np.exp(-bins/scale) /
(sps.gamma(shape)*scale**shape))
plt.plot(bins, y, linewidth=2, color='r')
plt.show()
I find that "y = bins*(shape-1)(np.exp(-bins/scale) / (sps.gamma(shape)scale
*shape))"
take very long time and the pop-up figure window becomes no-responding.
If I remove the lower and upper bounds for the gamma distribution, it runs
very fast.
Any help would be appreciated.
Thanks ! |
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