老規矩,貼源碼解釋
def nonzero(self):
"""nonzero indices
Returns a tuple of arrays (row,col) containing the indices
of the non-zero elements of the matrix.
返回包含矩陣的非零元素索引的數組(行、列)的元組
Examples
--------
>>> from scipy.sparse import csr_matrix
>>> A = csr_matrix([[1,2,0],[0,0,3],[4,0,5]])
>>> A.nonzero()
(array([0, 0, 1, 2, 2]), array([0, 1, 2, 0, 2]))
左邊的array代表行索引,右邊的array代表列索引,(行索引,列索引)代表一個矩陣元素
"""
# convert to COOrdinate format
A = self.tocoo()
nz_mask = A.data != 0
return (A.row[nz_mask], A.col[nz_mask])