Why is max and min of numpy array nan?

Question

What could be the reason, why the max and min of my numpy array is nan? I checked my array with:

for i in range(data[0]):
    if data[i] == numpy.nan:
        print("nan")    

And there is no nan in my data. Is my search wrong? If not: What could be the reason for max and min being nan?

Answer 1

Here you go:

import numpy as np

a = np.array([1, 2, 3, np.nan, 4])

print(f'a.max() = {a.max()}')
print(f'np.nanmax(a) = {np.nanmax(a)}')

print(f'a.min() = {a.min()}')
print(f'np.nanmin(a) = {np.nanmin(a)}')

Output:

a.max() = nan
np.nanmax(a) = 4.0
a.min() = nan
np.nanmin(a) = 1.0