[Python] Boolean Or "Mask" Index Arrays filter with numpy

NumPy Reference: Indexing

• Integer array indexing
• Boolean array indexing

Note: The expression a < mean produces a boolean array, like:

[[False, False, True, False, False, False, True, True, True],
 [True, True, False, False, True, True, False, True, True]]

def filter():
    a = np.array([
        (20,20,10,23,26,32,10,5,0),
        (0,2,50,20,0,1,28,5,0)
    ])

    mean = a.mean()
    print("mean",mean) #14.0
    print(a[a<mean]) #[10 10  5  0  0  2  0  1  5  0]

    # replace all which value which is less than mean value
    a[a<mean]=mean
    print(a)
    """
    [[20 20 14 23 26 32 14 14 14]
    [14 14 50 20 14 14 28 14 14]]
    """


if __name__ == "__main__":

    filter()