Python 使用 np.where np.errstate 和警告 'error' 的 numpy 运行时警告

Question

我不断收到关于除法的运行时警告。在下面的代码中，我使用了 from this forum and even imported warnings error from .

的答案

def alpha_n(V):
    with np.errstate(divide='ignore'):
        alph = np.where(V!= -55, 0.01*(V+55)/(1-np.exp(-0.1*(V+55))), 0.1)
    return alph

RuntimeWarning: invalid value encountered in true_divide

如何正确定义函数以避免警告？

Answer 1

In [26]: def alpha_n(V):
    ...:     with np.errstate(invalid='ignore'):
    ...:         alph = np.where(V!= -55, 0.01*(V+55)/(1-np.exp(-0.1*(V+55))), 0
    ...: .1)
    ...:     return alph
    ...: 
In [27]: alpha_n(np.array([1,2,3,-55]))
Out[27]: array([0.56207849, 0.5719136 , 0.58176131, 0.1       ])

除以 0 不同于无效值：

In [28]: 1/(1-np.exp(-0.1*(np.array([-55])+55)))
<ipython-input-28-ed83c58d75bb>:1: RuntimeWarning: divide by zero encountered in true_divide
  1/(1-np.exp(-0.1*(np.array([-55])+55)))
Out[28]: array([inf])
In [29]: 0/(1-np.exp(-0.1*(np.array([-55])+55)))
<ipython-input-29-0d642b423038>:1: RuntimeWarning: invalid value encountered in true_divide
  0/(1-np.exp(-0.1*(np.array([-55])+55)))
Out[29]: array([nan])

Python 使用 np.where np.errstate 和警告 'error' 的 numpy 运行时警告

Python numpy Runtime warning using np.where np.errstate and warnings 'error'

python

numpy

division