find max value of a list with numpy nan [duplicate

问题:

This question already has an answer here:

Numpy: Maximal Value is NaN (1 answer)

Closed 3 years ago.

import numpy as np

print max([np.nan, 1, 2, 3, 4])
print max([1, 2, 3, 4, np.nan])
print max([1, 2, 3, np.nan, 4])

the first will print nan as list's max value

the second will print 4 as list's max value

the third will print 4 as list's max value

Is there a solution for this problem? Make all math function just ignore nan?

回答1:

Use np.nanmax() to ignore any NaNs:

In [57]: np.nanmax([np.nan, 1, 2, 3, 4])
Out[57]: 4.0