Apply if statement function to 3D array numpy

Question

i have a 92x92x1 array in numpy, and for every value in this array, if the value is greater than 122, than it should be converted to 255, otherwise it should be converted to 0. Previously i have tried;

new_array=[]
for i in arr:
    column=[]
    for j in i:
        if j>122:
            temp=255
        else:
             temp=0
        column.append(j)
    new_array.append(column)
new_array=np.resize(np.array(new_array),(92,92,1))

but there must be a quicker, more elegant, and more pythonic way to do this! IS there any other method for mapping these types of functions to 3D arrays?

Nicolas Gervais · Accepted Answer · 2019-11-21 12:54:29Z

3

NumPy supports vectorized operations so you do not need a for-loop. You can use boolean indexing and it will apply to all dimensions.

import numpy as np

arr = np.random.randint(0, 255, (92, 92, 1))

arr[arr >= 122] = 255

arr[arr < 122] = 0

edited Nov 21, 2019 at 12:54

answered Nov 2, 2019 at 0:41

Nicolas Gervais

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2 Comments

3NiGMa Over a year ago

thanks @Nicolas Gervais, although i didn't need to initialise the array with random values, lines 3 and 4 answer the question anyway

Nicolas Gervais Over a year ago

It's so other people can easily reproduce the code and verify that it works in a second.

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