dask.array.triu_indices_from
dask.array.triu_indices_from¶
- dask.array.triu_indices_from(arr, k=0)[source]¶
Return the indices for the upper-triangle of arr.
This docstring was copied from numpy.triu_indices_from.
Some inconsistencies with the Dask version may exist.
See triu_indices for full details.
- Parameters
- arrndarray, shape(N, N)
The indices will be valid for square arrays.
- kint, optional
Diagonal offset (see triu for details).
- Returns
- triu_indices_fromtuple, shape(2) of ndarray, shape(N)
Indices for the upper-triangle of arr.
See also
Notes
New in version 1.4.0.
Examples
>>> import numpy as np
Create a 4 by 4 array
>>> a = np.arange(16).reshape(4, 4) >>> a array([[ 0, 1, 2, 3], [ 4, 5, 6, 7], [ 8, 9, 10, 11], [12, 13, 14, 15]])
Pass the array to get the indices of the upper triangular elements.
>>> triui = np.triu_indices_from(a) >>> triui (array([0, 0, 0, 0, 1, 1, 1, 2, 2, 3]), array([0, 1, 2, 3, 1, 2, 3, 2, 3, 3]))
>>> a[triui] array([ 0, 1, 2, 3, 5, 6, 7, 10, 11, 15])
This is syntactic sugar for triu_indices().
>>> np.triu_indices(a.shape[0]) (array([0, 0, 0, 0, 1, 1, 1, 2, 2, 3]), array([0, 1, 2, 3, 1, 2, 3, 2, 3, 3]))
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] array([ 1, 2, 3, 6, 7, 11])