`numpy:triu_indices_from`

Signature

def triu_indices_from ( arr , k = 0 )

Return the indices for the upper-triangle of arr.

See triu_indices for full details.

triu_indices_from : tuple, shape(2) of ndarray, shape(N): Indices for the upper-triangle of arr.

import numpy as np

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Create a 4 by 4 array

a = np.arange(16).reshape(4, 4)
a

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Pass the array to get the indices of the upper triangular elements.

triui = np.triu_indices_from(a)
triui

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a[triui]

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This is syntactic sugar for triu_indices().

np.triu_indices(a.shape[0])

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Use the `k` parameter to return the indices for the upper triangular array from the k-th diagonal.

triuim1 = np.triu_indices_from(a, k=1)
a[triuim1]

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