python random.gammavariate()，伽玛分布随机数

random.gammavariate()方法

random模块中的gammavariate()方法，可以用于获取一个伽玛分布的随机数。

语法

gammavariate( alpha, beta )

python源码中对该方法的介绍：

Gamma distribution.  Not the gamma function!
    
    Conditions on the parameters are alpha > 0 and beta > 0.
    
    The probability distribution function is:
    
                x ** (alpha - 1) * math.exp(-x / beta)
      pdf(x) =  --------------------------------------
                  math.gamma(alpha) * beta ** alpha

参数

gammavariate()方法必须接受两个参数，而且第一个参数alpha必须大于0, 第二个参数beta也必须大于0，否则python会抛出ValueError。如果不传递参数，python抛出TypeError

gammavariate()实例代码

>>> import random
>>> random.gammavariate(1,2)
2.2968181119351843
>>> random.gammavariate(-1,0) #若传递的参数小于或等于0，python抛出ValueError
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/anaconda3/lib/python3.7/random.py", line 522, in gammavariate
    raise ValueError('gammavariate: alpha and beta must be > 0.0')
ValueError: gammavariate: alpha and beta must be > 0.0
>>> random.gammavariate() #不传递参数的情况下，python抛出TypeError
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: gammavariate() missing 2 required positional arguments: 'alpha' and 'beta'

hot：热门