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bundles / scipy 1.18.0 / scipy / sparse / _extract / tril

function

scipy.sparse._extract:tril

source: /scipy/sparse/_extract.py:48

Signature

def tril(A, k = 0, format = None)

Summary

Return the lower triangular portion of a sparse array or matrix.

Extended Summary

Returns the elements on or below 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

A : dense or sparse array or matrix

Matrix whose lower trianglar portion is desired.

k : int : optional

The top-most diagonal of the lower triangle.

format : str

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

Returns

L : sparse matrix

Lower triangular portion of A in sparse format.

Examples

from scipy.sparse import csr_array, tril
A = csr_array([[1, 2, 0, 0, 3], [4, 5, 0, 6, 7], [0, 0, 8, 9, 0]],
              dtype='int32')
A.toarray()
tril(A).toarray()
tril(A).nnz
tril(A, k=1).toarray()
tril(A, k=-1).toarray()
✓
array([[0, 0, 0, 0, 0],
       [4, 0, 0, 0, 0],
       [0, 0, 0, 0, 0]], dtype=int32)

tril(A, format='csc')
✗
<Compressed Sparse Column sparse array of dtype 'int32'
	with 4 stored elements and shape (3, 5)>

See also

triu

upper triangle in sparse format

Aliases

  • scipy.sparse.tril

Referenced by

This package