triu — SciPy v1.15.3 Manual (original) (raw)

scipy.sparse.

scipy.sparse.triu(A, k=0, format=None)[source]#

Return the upper triangular portion of a sparse array or matrix

Returns the elements on or above the k-th diagonal of A.

• k = 0 corresponds to the main diagonal
• k > 0 is above the main diagonal
• k < 0 is below the main diagonal

Parameters:

Adense or sparse array or matrix

Matrix whose upper trianglar portion is desired.

kintegeroptional

The bottom-most diagonal of the upper triangle.

formatstring

Sparse format of the result, e.g. format=”csr”, etc.

Returns:

Lsparse array or matrix

Upper triangular portion of A in sparse format. Sparse array if A is a sparse array, otherwise matrix.

See also

tril

lower triangle in sparse format

Examples

from scipy.sparse import csr_array, triu A = csr_array([[1, 2, 0, 0, 3], [4, 5, 0, 6, 7], [0, 0, 8, 9, 0]], ... dtype='int32') A.toarray() array([[1, 2, 0, 0, 3], [4, 5, 0, 6, 7], [0, 0, 8, 9, 0]], dtype=int32) triu(A).toarray() array([[1, 2, 0, 0, 3], [0, 5, 0, 6, 7], [0, 0, 8, 9, 0]], dtype=int32) triu(A).nnz 8 triu(A, k=1).toarray() array([[0, 2, 0, 0, 3], [0, 0, 0, 6, 7], [0, 0, 0, 9, 0]], dtype=int32) triu(A, k=-1).toarray() array([[1, 2, 0, 0, 3], [4, 5, 0, 6, 7], [0, 0, 8, 9, 0]], dtype=int32) triu(A, format='csc') <Compressed Sparse Column sparse array of dtype 'int32' with 8 stored elements and shape (3, 5)>