如何在间隔中分离随机数，然后获得python间隔的概率？

Question

我必须使用python中的numpy生成2000浮点随机数，然后获得这些数字的整数间隔，并最终计算频率和概率。

有人可以帮我吗？

Answer 1

iiuc，我们知道正态分布中（-1,1）之间的概率为68％，如果我们测试，我们会发现这是正确的：

import matplotlib.pyplot as plt
import numpy as np

mu, sigma = 0, 1 # mean and standard deviation
rnorm = np.random.normal(mu, sigma, 2000)

freq = np.sum(np.logical_and(rnorm>=-1, rnorm<=1))
print(f'frequency between (-1,1): {(freq)}')

prob = freq/2000*100
print(f'probability between (-1,1): {prob} %')

# Or (-2,2) is 95% and (-3,3) is 99.7 like below:
# >>> np.sum(np.logical_and(rnorm>=-2, rnorm<=2))/2000*100
# 95.85000000000001
# >>> np.sum(np.logical_and(rnorm>=-3, rnorm<=3))/2000*100
# 99.7

输出：

frequency between (-1,1): 1365
probability between (-1,1): 68.25 %

您可以使用plt.hist.hist （您可以根据需要更改bin），然后计算以下类似于下面的频率和概率：

plt.hist(rnorm, bins=50)
plt.show()

freq = rnorm[rnorm < 0]
print(f'frequency less than ZERO: {len(freq)}')

prob = rnorm[rnorm < 0]
print(f'probability less than ZERO: {len(freq)/2000*100} %')

frequency less than ZERO: 1003
probability less than ZERO: 50.14999999999999 %