Combining two numpy arrays to form an array with the largest value from each array

You can use np.maximum to compute the element-wise maximum of the two arrays:

>>> np.maximum(a, b)array([[ 0. ,  0. ,  0.5],       [ 0.5,  0.5,  0.5],       [ 0.5,  0.1,  0. ]])

This works with any two arrays, as long as they're the same shape or one can be broadcast to the shape of the other.

To modify the array a in-place, you can redirect the output of np.maximum back to a:

np.maximum(a, b, out=a)

There is also np.minimum for calculating the element-wise minimum of two arrays.

python arrays numpy max

You are looking for the element-wise maximum.

Example:

>>> np.maximum([2, 3, 4], [1, 5, 2])array([2, 5, 4])

python arrays numpy max

inds =  b > aa[inds] = b[inds]

This modifies the original array a which is what += is doing in your example which may or may not be what you want.

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