Sparse matrices

CuPy supports sparse matrices using cuSPARSE. These matrices have the same interfaces of SciPy’s sparse matrices.

Conversion to/from SciPy sparse matrices

cupyx.scipy.sparse.*_matrix and cupyx.scipy.sparse.*_matrix are not implicitly convertible to each other. That means, SciPy functions cannot take cupyx.scipy.sparse.*_matrix objects as inputs, and vice versa.

  • To convert SciPy sparse matrices to CuPy, pass it to the constructor of each CuPy sparse matrix class.
  • To convert CuPy sparse matrices to SciPy, use get method of each CuPy sparse matrix class.

Note that converting between CuPy and SciPy incurs data transfer between the host (CPU) device and the GPU device, which is costly in terms of performance.

Conversion to/from CuPy ndarrays

  • To convert CuPy ndarray to CuPy sparse matrices, pass it to the constructor of each CuPy sparse matrix class.
  • To convert CuPy sparse matrices to CuPy ndarray, use toarray of each CuPy sparse matrix instance (e.g., cupyx.scipy.sparse.csr_matrix.toarray()).

Converting between CuPy ndarray and CuPy sparse matrices does not incur data transfer; it is copied inside the GPU device.

Sparse matrix classes

cupyx.scipy.sparse.coo_matrix COOrdinate format sparse matrix.
cupyx.scipy.sparse.csr_matrix Compressed Sparse Row matrix.
cupyx.scipy.sparse.csc_matrix Compressed Sparse Column matrix.
cupyx.scipy.sparse.dia_matrix Sparse matrix with DIAgonal storage.
cupyx.scipy.sparse.spmatrix Base class of all sparse matrixes.

Functions

Building sparse matrices

cupyx.scipy.sparse.eye Creates a sparse matrix with ones on diagonal.
cupyx.scipy.sparse.identity Creates an identity matrix in sparse format.
cupyx.scipy.sparse.spdiags Creates a sparse matrix from diagonals.
cupyx.scipy.sparse.rand Generates a random sparse matrix.
cupyx.scipy.sparse.random Generates a random sparse matrix.

Identifying sparse matrices

cupyx.scipy.sparse.issparse Checks if a given matrix is a sparse matrix.
cupyx.scipy.sparse.isspmatrix Checks if a given matrix is a sparse matrix.
cupyx.scipy.sparse.isspmatrix_csc Checks if a given matrix is of CSC format.
cupyx.scipy.sparse.isspmatrix_csr Checks if a given matrix is of CSR format.
cupyx.scipy.sparse.isspmatrix_coo Checks if a given matrix is of COO format.
cupyx.scipy.sparse.isspmatrix_dia Checks if a given matrix is of DIA format.

Linear Algebra

cupyx.scipy.sparse.linalg.lsqr Solves linear system with QR decomposition.