python 用数组替换操作后的 NaN 值零
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replace the NaN value zero after an operation with arrays
提问by ricardo
how can I replace the NaN value in an array, zero if an operation is performed such that as a result instead of the NaN value is zero operations as
如何替换数组中的 NaN 值，如果执行操作则为零，因此结果而不是 NaN 值是零操作，如
0 / 0 = NaN can be replaced by 0
0 / 0 = NaN 可以替换为 0
回答by Dave Webb
If you have Python 2.6 you have the math.isnan()function to find NaNvalues.
如果你有 Python 2.6，你就有math.isnan()查找NaN值的功能。
With this we can use a list comprehension to replace the NaNvalues in a list as follows:
有了这个，我们可以使用列表理解来替换列表中的NaN值，如下所示：
import math
mylist = [0 if math.isnan(x) else x for x in mylist]
If you have Python 2.5 we can use the NaN != NaNtrick from this questionso you do this:
如果你有 Python 2.5，我们可以使用这个问题中的NaN != NaN技巧，所以你可以这样做：
mylist = [0 if x != x else x for x in mylist]
回答by SoonSYJ
import numpy
a=numpy.array([1,2,3,'NaN',4])
s=numpy.isnan(a)
a[s]=0.0
