获取平均值以避免在python中使用numpy的nan

问题描述

如何计算避免nan的数组(A)的平均值?

How to calculate mean value of an array (A) avoiding nan?

import numpy as np
A = [5    nan    nan    nan    nan  10]
M = np.mean(A[A!=nan]) does not work
Any idea?

推荐答案

使用 :

>>> import numpy as np
>>> A = np.array([5, np.nan, np.nan, np.nan, np.nan, 10])
>>> np.isnan(A)
array([False,  True,  True,  True,  True, False], dtype=bool)
>>> ~np.isnan(A)
array([ True, False, False, False, False,  True], dtype=bool)
>>> A[~np.isnan(A)]
array([  5.,  10.])
>>> A[~np.isnan(A)].mean()
7.5

因为您无法将nan与nan进行比较:

because you cannot compare nan with nan:

>>> np.nan == np.nan
False
>>> np.nan != np.nan
True
>>> np.isnan(np.nan)
True

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