sklearn.utils.extmath.safe_sparse_dot

sklearn.utils.extmath.safe_sparse_dot(a, b, *, dense_output=False)[source]

Dot product that handle the sparse matrix case correctly.

Parameters:
a{ndarray, sparse matrix}
b{ndarray, sparse matrix}
dense_outputbool, default=False

When False, a and b both being sparse will yield sparse output. When True, output will always be a dense array.

Returns:
dot_product{ndarray, sparse matrix}

Sparse if a and b are sparse and dense_output=False.

Examples

>>> from scipy.sparse import csr_matrix
>>> from sklearn.utils.extmath import safe_sparse_dot
>>> X = csr_matrix([[1, 2], [3, 4], [5, 6]])
>>> dot_product = safe_sparse_dot(X, X.T)
>>> dot_product.toarray()
array([[ 5, 11, 17],
       [11, 25, 39],
       [17, 39, 61]])