path: root/src/arrow/python/pyarrow/tensor.pxi

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# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.


cdef class Tensor(_Weakrefable):
    """
    A n-dimensional array a.k.a Tensor.
    """

    def __init__(self):
        raise TypeError("Do not call Tensor's constructor directly, use one "
                        "of the `pyarrow.Tensor.from_*` functions instead.")

    cdef void init(self, const shared_ptr[CTensor]& sp_tensor):
        self.sp_tensor = sp_tensor
        self.tp = sp_tensor.get()
        self.type = pyarrow_wrap_data_type(self.tp.type())

    def __repr__(self):
        return """<pyarrow.Tensor>
type: {0.type}
shape: {0.shape}
strides: {0.strides}""".format(self)

    @staticmethod
    def from_numpy(obj, dim_names=None):
        """
        Create a Tensor from a numpy array.

        Parameters
        ----------
        obj : numpy.ndarray
            The source numpy array
        dim_names : list, optional
            Names of each dimension of the Tensor.
        """
        cdef:
            vector[c_string] c_dim_names
            shared_ptr[CTensor] ctensor

        if dim_names is not None:
            for x in dim_names:
                c_dim_names.push_back(tobytes(x))

        check_status(NdarrayToTensor(c_default_memory_pool(), obj,
                                     c_dim_names, &ctensor))
        return pyarrow_wrap_tensor(ctensor)

    def to_numpy(self):
        """
        Convert arrow::Tensor to numpy.ndarray with zero copy
        """
        cdef PyObject* out

        check_status(TensorToNdarray(self.sp_tensor, self, &out))
        return PyObject_to_object(out)

    def equals(self, Tensor other):
        """
        Return true if the tensors contains exactly equal data
        """
        return self.tp.Equals(deref(other.tp))

    def __eq__(self, other):
        if isinstance(other, Tensor):
            return self.equals(other)
        else:
            return NotImplemented

    def dim_name(self, i):
        return frombytes(self.tp.dim_name(i))

    @property
    def dim_names(self):
        return [frombytes(x) for x in tuple(self.tp.dim_names())]

    @property
    def is_mutable(self):
        return self.tp.is_mutable()

    @property
    def is_contiguous(self):
        return self.tp.is_contiguous()

    @property
    def ndim(self):
        return self.tp.ndim()

    @property
    def size(self):
        return self.tp.size()

    @property
    def shape(self):
        # Cython knows how to convert a vector[T] to a Python list
        return tuple(self.tp.shape())

    @property
    def strides(self):
        return tuple(self.tp.strides())

    def __getbuffer__(self, cp.Py_buffer* buffer, int flags):
        buffer.buf = <char *> self.tp.data().get().data()
        pep3118_format = self.type.pep3118_format
        if pep3118_format is None:
            raise NotImplementedError("type %s not supported for buffer "
                                      "protocol" % (self.type,))
        buffer.format = pep3118_format
        buffer.itemsize = self.type.bit_width // 8
        buffer.internal = NULL
        buffer.len = self.tp.size() * buffer.itemsize
        buffer.ndim = self.tp.ndim()
        buffer.obj = self
        if self.tp.is_mutable():
            buffer.readonly = 0
        else:
            buffer.readonly = 1
        # NOTE: This assumes Py_ssize_t == int64_t, and that the shape
        # and strides arrays lifetime is tied to the tensor's
        buffer.shape = <Py_ssize_t *> &self.tp.shape()[0]
        buffer.strides = <Py_ssize_t *> &self.tp.strides()[0]
        buffer.suboffsets = NULL


ctypedef CSparseCOOIndex* _CSparseCOOIndexPtr


cdef class SparseCOOTensor(_Weakrefable):
    """
    A sparse COO tensor.
    """

    def __init__(self):
        raise TypeError("Do not call SparseCOOTensor's constructor directly, "
                        "use one of the `pyarrow.SparseCOOTensor.from_*` "
                        "functions instead.")

    cdef void init(self, const shared_ptr[CSparseCOOTensor]& sp_sparse_tensor):
        self.sp_sparse_tensor = sp_sparse_tensor
        self.stp = sp_sparse_tensor.get()
        self.type = pyarrow_wrap_data_type(self.stp.type())

    def __repr__(self):
        return """<pyarrow.SparseCOOTensor>
type: {0.type}
shape: {0.shape}""".format(self)

    @classmethod
    def from_dense_numpy(cls, obj, dim_names=None):
        """
        Convert numpy.ndarray to arrow::SparseCOOTensor
        """
        return cls.from_tensor(Tensor.from_numpy(obj, dim_names=dim_names))

    @staticmethod
    def from_numpy(data, coords, shape, dim_names=None):
        """
        Create arrow::SparseCOOTensor from numpy.ndarrays

        Parameters
        ----------
        data : numpy.ndarray
            Data used to populate the rows.
        coords : numpy.ndarray
            Coordinates of the data.
        shape : tuple
            Shape of the tensor.
        dim_names : list, optional
            Names of the dimensions.
        """
        cdef shared_ptr[CSparseCOOTensor] csparse_tensor
        cdef vector[int64_t] c_shape
        cdef vector[c_string] c_dim_names

        for x in shape:
            c_shape.push_back(x)
        if dim_names is not None:
            for x in dim_names:
                c_dim_names.push_back(tobytes(x))

        # Enforce precondition for SparseCOOTensor indices
        coords = np.require(coords, dtype='i8', requirements='C')
        if coords.ndim != 2:
            raise ValueError("Expected 2-dimensional array for "
                             "SparseCOOTensor indices")

        check_status(NdarraysToSparseCOOTensor(c_default_memory_pool(),
                                               data, coords, c_shape,
                                               c_dim_names, &csparse_tensor))
        return pyarrow_wrap_sparse_coo_tensor(csparse_tensor)

    @staticmethod
    def from_scipy(obj, dim_names=None):
        """
        Convert scipy.sparse.coo_matrix to arrow::SparseCOOTensor

        Parameters
        ----------
        obj : scipy.sparse.csr_matrix
            The scipy matrix that should be converted.
        dim_names : list, optional
            Names of the dimensions.
        """
        import scipy.sparse
        if not isinstance(obj, scipy.sparse.coo_matrix):
            raise TypeError(
                "Expected scipy.sparse.coo_matrix, got {}".format(type(obj)))

        cdef shared_ptr[CSparseCOOTensor] csparse_tensor
        cdef vector[int64_t] c_shape
        cdef vector[c_string] c_dim_names

        for x in obj.shape:
            c_shape.push_back(x)
        if dim_names is not None:
            for x in dim_names:
                c_dim_names.push_back(tobytes(x))

        row = obj.row
        col = obj.col

        # When SciPy's coo_matrix has canonical format, its indices matrix is
        # sorted in column-major order.  As Arrow's SparseCOOIndex is sorted
        # in row-major order if it is canonical, we must sort indices matrix
        # into row-major order to keep its canonicalness, here.
        if obj.has_canonical_format:
            order = np.lexsort((col, row))  # sort in row-major order
            row = row[order]
            col = col[order]
        coords = np.vstack([row, col]).T
        coords = np.require(coords, dtype='i8', requirements='C')

        check_status(NdarraysToSparseCOOTensor(c_default_memory_pool(),
                                               obj.data, coords, c_shape,
                                               c_dim_names, &csparse_tensor))
        return pyarrow_wrap_sparse_coo_tensor(csparse_tensor)

    @staticmethod
    def from_pydata_sparse(obj, dim_names=None):
        """
        Convert pydata/sparse.COO to arrow::SparseCOOTensor.

        Parameters
        ----------
        obj : pydata.sparse.COO
            The sparse multidimensional array that should be converted.
        dim_names : list, optional
            Names of the dimensions.
        """
        import sparse
        if not isinstance(obj, sparse.COO):
            raise TypeError(
                "Expected sparse.COO, got {}".format(type(obj)))

        cdef shared_ptr[CSparseCOOTensor] csparse_tensor
        cdef vector[int64_t] c_shape
        cdef vector[c_string] c_dim_names

        for x in obj.shape:
            c_shape.push_back(x)
        if dim_names is not None:
            for x in dim_names:
                c_dim_names.push_back(tobytes(x))

        coords = np.require(obj.coords.T, dtype='i8', requirements='C')

        check_status(NdarraysToSparseCOOTensor(c_default_memory_pool(),
                                               obj.data, coords, c_shape,
                                               c_dim_names, &csparse_tensor))
        return pyarrow_wrap_sparse_coo_tensor(csparse_tensor)

    @staticmethod
    def from_tensor(obj):
        """
        Convert arrow::Tensor to arrow::SparseCOOTensor.

        Parameters
        ----------
        obj : Tensor
            The tensor that should be converted.
        """
        cdef shared_ptr[CSparseCOOTensor] csparse_tensor
        cdef shared_ptr[CTensor] ctensor = pyarrow_unwrap_tensor(obj)

        with nogil:
            check_status(TensorToSparseCOOTensor(ctensor, &csparse_tensor))

        return pyarrow_wrap_sparse_coo_tensor(csparse_tensor)

    def to_numpy(self):
        """
        Convert arrow::SparseCOOTensor to numpy.ndarrays with zero copy.
        """
        cdef PyObject* out_data
        cdef PyObject* out_coords

        check_status(SparseCOOTensorToNdarray(self.sp_sparse_tensor, self,
                                              &out_data, &out_coords))
        return PyObject_to_object(out_data), PyObject_to_object(out_coords)

    def to_scipy(self):
        """
        Convert arrow::SparseCOOTensor to scipy.sparse.coo_matrix.
        """
        from scipy.sparse import coo_matrix
        cdef PyObject* out_data
        cdef PyObject* out_coords

        check_status(SparseCOOTensorToNdarray(self.sp_sparse_tensor, self,
                                              &out_data, &out_coords))
        data = PyObject_to_object(out_data)
        coords = PyObject_to_object(out_coords)
        row, col = coords[:, 0], coords[:, 1]
        result = coo_matrix((data[:, 0], (row, col)), shape=self.shape)

        # As the description in from_scipy above, we sorted indices matrix
        # in row-major order if SciPy's coo_matrix has canonical format.
        # So, we must call sum_duplicates() to make the result coo_matrix
        # has canonical format.
        if self.has_canonical_format:
            result.sum_duplicates()
        return result

    def to_pydata_sparse(self):
        """
        Convert arrow::SparseCOOTensor to pydata/sparse.COO.
        """
        from sparse import COO
        cdef PyObject* out_data
        cdef PyObject* out_coords

        check_status(SparseCOOTensorToNdarray(self.sp_sparse_tensor, self,
                                              &out_data, &out_coords))
        data = PyObject_to_object(out_data)
        coords = PyObject_to_object(out_coords)
        result = COO(data=data[:, 0], coords=coords.T, shape=self.shape)
        return result

    def to_tensor(self):
        """
        Convert arrow::SparseCOOTensor to arrow::Tensor.
        """

        cdef shared_ptr[CTensor] ctensor
        with nogil:
            ctensor = GetResultValue(self.stp.ToTensor())

        return pyarrow_wrap_tensor(ctensor)

    def equals(self, SparseCOOTensor other):
        """
        Return true if sparse tensors contains exactly equal data.
        """
        return self.stp.Equals(deref(other.stp))

    def __eq__(self, other):
        if isinstance(other, SparseCOOTensor):
            return self.equals(other)
        else:
            return NotImplemented

    @property
    def is_mutable(self):
        return self.stp.is_mutable()

    @property
    def ndim(self):
        return self.stp.ndim()

    @property
    def shape(self):
        # Cython knows how to convert a vector[T] to a Python list
        return tuple(self.stp.shape())

    @property
    def size(self):
        return self.stp.size()

    def dim_name(self, i):
        return frombytes(self.stp.dim_name(i))

    @property
    def dim_names(self):
        return tuple(frombytes(x) for x in tuple(self.stp.dim_names()))

    @property
    def non_zero_length(self):
        return self.stp.non_zero_length()

    @property
    def has_canonical_format(self):
        cdef:
            _CSparseCOOIndexPtr csi

        csi = <_CSparseCOOIndexPtr>(self.stp.sparse_index().get())
        if csi != nullptr:
            return csi.is_canonical()
        return True

cdef class SparseCSRMatrix(_Weakrefable):
    """
    A sparse CSR matrix.
    """

    def __init__(self):
        raise TypeError("Do not call SparseCSRMatrix's constructor directly, "
                        "use one of the `pyarrow.SparseCSRMatrix.from_*` "
                        "functions instead.")

    cdef void init(self, const shared_ptr[CSparseCSRMatrix]& sp_sparse_tensor):
        self.sp_sparse_tensor = sp_sparse_tensor
        self.stp = sp_sparse_tensor.get()
        self.type = pyarrow_wrap_data_type(self.stp.type())

    def __repr__(self):
        return """<pyarrow.SparseCSRMatrix>
type: {0.type}
shape: {0.shape}""".format(self)

    @classmethod
    def from_dense_numpy(cls, obj, dim_names=None):
        """
        Convert numpy.ndarray to arrow::SparseCSRMatrix

        Parameters
        ----------
        obj : numpy.ndarray
            The dense numpy array that should be converted.
        dim_names : list, optional
            The names of the dimensions.
        """
        return cls.from_tensor(Tensor.from_numpy(obj, dim_names=dim_names))

    @staticmethod
    def from_numpy(data, indptr, indices, shape, dim_names=None):
        """
        Create arrow::SparseCSRMatrix from numpy.ndarrays.

        Parameters
        ----------
        data : numpy.ndarray
            Data used to populate the sparse matrix.
        indptr : numpy.ndarray
            Range of the rows,
            The i-th row spans from `indptr[i]` to `indptr[i+1]` in the data.
        indices : numpy.ndarray
            Column indices of the corresponding non-zero values.
        shape : tuple
            Shape of the matrix.
        dim_names : list, optional
            Names of the dimensions.
        """
        cdef shared_ptr[CSparseCSRMatrix] csparse_tensor
        cdef vector[int64_t] c_shape
        cdef vector[c_string] c_dim_names

        for x in shape:
            c_shape.push_back(x)
        if dim_names is not None:
            for x in dim_names:
                c_dim_names.push_back(tobytes(x))

        # Enforce precondition for SparseCSRMatrix indices
        indptr = np.require(indptr, dtype='i8')
        indices = np.require(indices, dtype='i8')
        if indptr.ndim != 1:
            raise ValueError("Expected 1-dimensional array for "
                             "SparseCSRMatrix indptr")
        if indices.ndim != 1:
            raise ValueError("Expected 1-dimensional array for "
                             "SparseCSRMatrix indices")

        check_status(NdarraysToSparseCSRMatrix(c_default_memory_pool(),
                                               data, indptr, indices, c_shape,
                                               c_dim_names, &csparse_tensor))
        return pyarrow_wrap_sparse_csr_matrix(csparse_tensor)

    @staticmethod
    def from_scipy(obj, dim_names=None):
        """
        Convert scipy.sparse.csr_matrix to arrow::SparseCSRMatrix.

        Parameters
        ----------
        obj : scipy.sparse.csr_matrix
            The scipy matrix that should be converted.
        dim_names : list, optional
            Names of the dimensions.
        """
        import scipy.sparse
        if not isinstance(obj, scipy.sparse.csr_matrix):
            raise TypeError(
                "Expected scipy.sparse.csr_matrix, got {}".format(type(obj)))

        cdef shared_ptr[CSparseCSRMatrix] csparse_tensor
        cdef vector[int64_t] c_shape
        cdef vector[c_string] c_dim_names

        for x in obj.shape:
            c_shape.push_back(x)
        if dim_names is not None:
            for x in dim_names:
                c_dim_names.push_back(tobytes(x))

        # Enforce precondition for CSparseCSRMatrix indices
        indptr = np.require(obj.indptr, dtype='i8')
        indices = np.require(obj.indices, dtype='i8')

        check_status(NdarraysToSparseCSRMatrix(c_default_memory_pool(),
                                               obj.data, indptr, indices,
                                               c_shape, c_dim_names,
                                               &csparse_tensor))
        return pyarrow_wrap_sparse_csr_matrix(csparse_tensor)

    @staticmethod
    def from_tensor(obj):
        """
        Convert arrow::Tensor to arrow::SparseCSRMatrix.

        Parameters
        ----------
        obj : Tensor
            The dense tensor that should be converted.
        """
        cdef shared_ptr[CSparseCSRMatrix] csparse_tensor
        cdef shared_ptr[CTensor] ctensor = pyarrow_unwrap_tensor(obj)

        with nogil:
            check_status(TensorToSparseCSRMatrix(ctensor, &csparse_tensor))

        return pyarrow_wrap_sparse_csr_matrix(csparse_tensor)

    def to_numpy(self):
        """
        Convert arrow::SparseCSRMatrix to numpy.ndarrays with zero copy.
        """
        cdef PyObject* out_data
        cdef PyObject* out_indptr
        cdef PyObject* out_indices

        check_status(SparseCSRMatrixToNdarray(self.sp_sparse_tensor, self,
                                              &out_data, &out_indptr,
                                              &out_indices))
        return (PyObject_to_object(out_data), PyObject_to_object(out_indptr),
                PyObject_to_object(out_indices))

    def to_scipy(self):
        """
        Convert arrow::SparseCSRMatrix to scipy.sparse.csr_matrix.
        """
        from scipy.sparse import csr_matrix
        cdef PyObject* out_data
        cdef PyObject* out_indptr
        cdef PyObject* out_indices

        check_status(SparseCSRMatrixToNdarray(self.sp_sparse_tensor, self,
                                              &out_data, &out_indptr,
                                              &out_indices))

        data = PyObject_to_object(out_data)
        indptr = PyObject_to_object(out_indptr)
        indices = PyObject_to_object(out_indices)
        result = csr_matrix((data[:, 0], indices, indptr), shape=self.shape)
        return result

    def to_tensor(self):
        """
        Convert arrow::SparseCSRMatrix to arrow::Tensor.
        """
        cdef shared_ptr[CTensor] ctensor
        with nogil:
            ctensor = GetResultValue(self.stp.ToTensor())

        return pyarrow_wrap_tensor(ctensor)

    def equals(self, SparseCSRMatrix other):
        """
        Return true if sparse tensors contains exactly equal data.
        """
        return self.stp.Equals(deref(other.stp))

    def __eq__(self, other):
        if isinstance(other, SparseCSRMatrix):
            return self.equals(other)
        else:
            return NotImplemented

    @property
    def is_mutable(self):
        return self.stp.is_mutable()

    @property
    def ndim(self):
        return self.stp.ndim()

    @property
    def shape(self):
        # Cython knows how to convert a vector[T] to a Python list
        return tuple(self.stp.shape())

    @property
    def size(self):
        return self.stp.size()

    def dim_name(self, i):
        return frombytes(self.stp.dim_name(i))

    @property
    def dim_names(self):
        return tuple(frombytes(x) for x in tuple(self.stp.dim_names()))

    @property
    def non_zero_length(self):
        return self.stp.non_zero_length()

cdef class SparseCSCMatrix(_Weakrefable):
    """
    A sparse CSC matrix.
    """

    def __init__(self):
        raise TypeError("Do not call SparseCSCMatrix's constructor directly, "
                        "use one of the `pyarrow.SparseCSCMatrix.from_*` "
                        "functions instead.")

    cdef void init(self, const shared_ptr[CSparseCSCMatrix]& sp_sparse_tensor):
        self.sp_sparse_tensor = sp_sparse_tensor
        self.stp = sp_sparse_tensor.get()
        self.type = pyarrow_wrap_data_type(self.stp.type())

    def __repr__(self):
        return """<pyarrow.SparseCSCMatrix>
type: {0.type}
shape: {0.shape}""".format(self)

    @classmethod
    def from_dense_numpy(cls, obj, dim_names=None):
        """
        Convert numpy.ndarray to arrow::SparseCSCMatrix
        """
        return cls.from_tensor(Tensor.from_numpy(obj, dim_names=dim_names))

    @staticmethod
    def from_numpy(data, indptr, indices, shape, dim_names=None):
        """
        Create arrow::SparseCSCMatrix from numpy.ndarrays

        Parameters
        ----------
        data : numpy.ndarray
            Data used to populate the sparse matrix.
        indptr : numpy.ndarray
            Range of the rows,
            The i-th row spans from `indptr[i]` to `indptr[i+1]` in the data.
        indices : numpy.ndarray
            Column indices of the corresponding non-zero values.
        shape : tuple
            Shape of the matrix.
        dim_names : list, optional
            Names of the dimensions.
        """
        cdef shared_ptr[CSparseCSCMatrix] csparse_tensor
        cdef vector[int64_t] c_shape
        cdef vector[c_string] c_dim_names

        for x in shape:
            c_shape.push_back(x)
        if dim_names is not None:
            for x in dim_names:
                c_dim_names.push_back(tobytes(x))

        # Enforce precondition for SparseCSCMatrix indices
        indptr = np.require(indptr, dtype='i8')
        indices = np.require(indices, dtype='i8')
        if indptr.ndim != 1:
            raise ValueError("Expected 1-dimensional array for "
                             "SparseCSCMatrix indptr")
        if indices.ndim != 1:
            raise ValueError("Expected 1-dimensional array for "
                             "SparseCSCMatrix indices")

        check_status(NdarraysToSparseCSCMatrix(c_default_memory_pool(),
                                               data, indptr, indices, c_shape,
                                               c_dim_names, &csparse_tensor))
        return pyarrow_wrap_sparse_csc_matrix(csparse_tensor)

    @staticmethod
    def from_scipy(obj, dim_names=None):
        """
        Convert scipy.sparse.csc_matrix to arrow::SparseCSCMatrix

        Parameters
        ----------
        obj : scipy.sparse.csc_matrix
            The scipy matrix that should be converted.
        dim_names : list, optional
            Names of the dimensions.
        """
        import scipy.sparse
        if not isinstance(obj, scipy.sparse.csc_matrix):
            raise TypeError(
                "Expected scipy.sparse.csc_matrix, got {}".format(type(obj)))

        cdef shared_ptr[CSparseCSCMatrix] csparse_tensor
        cdef vector[int64_t] c_shape
        cdef vector[c_string] c_dim_names

        for x in obj.shape:
            c_shape.push_back(x)
        if dim_names is not None:
            for x in dim_names:
                c_dim_names.push_back(tobytes(x))

        # Enforce precondition for CSparseCSCMatrix indices
        indptr = np.require(obj.indptr, dtype='i8')
        indices = np.require(obj.indices, dtype='i8')

        check_status(NdarraysToSparseCSCMatrix(c_default_memory_pool(),
                                               obj.data, indptr, indices,
                                               c_shape, c_dim_names,
                                               &csparse_tensor))
        return pyarrow_wrap_sparse_csc_matrix(csparse_tensor)

    @staticmethod
    def from_tensor(obj):
        """
        Convert arrow::Tensor to arrow::SparseCSCMatrix

        Parameters
        ----------
        obj : Tensor
            The dense tensor that should be converted.
        """
        cdef shared_ptr[CSparseCSCMatrix] csparse_tensor
        cdef shared_ptr[CTensor] ctensor = pyarrow_unwrap_tensor(obj)

        with nogil:
            check_status(TensorToSparseCSCMatrix(ctensor, &csparse_tensor))

        return pyarrow_wrap_sparse_csc_matrix(csparse_tensor)

    def to_numpy(self):
        """
        Convert arrow::SparseCSCMatrix to numpy.ndarrays with zero copy
        """
        cdef PyObject* out_data
        cdef PyObject* out_indptr
        cdef PyObject* out_indices

        check_status(SparseCSCMatrixToNdarray(self.sp_sparse_tensor, self,
                                              &out_data, &out_indptr,
                                              &out_indices))
        return (PyObject_to_object(out_data), PyObject_to_object(out_indptr),
                PyObject_to_object(out_indices))

    def to_scipy(self):
        """
        Convert arrow::SparseCSCMatrix to scipy.sparse.csc_matrix
        """
        from scipy.sparse import csc_matrix
        cdef PyObject* out_data
        cdef PyObject* out_indptr
        cdef PyObject* out_indices

        check_status(SparseCSCMatrixToNdarray(self.sp_sparse_tensor, self,
                                              &out_data, &out_indptr,
                                              &out_indices))

        data = PyObject_to_object(out_data)
        indptr = PyObject_to_object(out_indptr)
        indices = PyObject_to_object(out_indices)
        result = csc_matrix((data[:, 0], indices, indptr), shape=self.shape)
        return result

    def to_tensor(self):
        """
        Convert arrow::SparseCSCMatrix to arrow::Tensor
        """

        cdef shared_ptr[CTensor] ctensor
        with nogil:
            ctensor = GetResultValue(self.stp.ToTensor())

        return pyarrow_wrap_tensor(ctensor)

    def equals(self, SparseCSCMatrix other):
        """
        Return true if sparse tensors contains exactly equal data
        """
        return self.stp.Equals(deref(other.stp))

    def __eq__(self, other):
        if isinstance(other, SparseCSCMatrix):
            return self.equals(other)
        else:
            return NotImplemented

    @property
    def is_mutable(self):
        return self.stp.is_mutable()

    @property
    def ndim(self):
        return self.stp.ndim()

    @property
    def shape(self):
        # Cython knows how to convert a vector[T] to a Python list
        return tuple(self.stp.shape())

    @property
    def size(self):
        return self.stp.size()

    def dim_name(self, i):
        return frombytes(self.stp.dim_name(i))

    @property
    def dim_names(self):
        return tuple(frombytes(x) for x in tuple(self.stp.dim_names()))

    @property
    def non_zero_length(self):
        return self.stp.non_zero_length()


cdef class SparseCSFTensor(_Weakrefable):
    """
    A sparse CSF tensor.

    CSF is a generalization of compressed sparse row (CSR) index.

    CSF index recursively compresses each dimension of a tensor into a set
    of prefix trees. Each path from a root to leaf forms one tensor
    non-zero index. CSF is implemented with two arrays of buffers and one
    arrays of integers.
    """

    def __init__(self):
        raise TypeError("Do not call SparseCSFTensor's constructor directly, "
                        "use one of the `pyarrow.SparseCSFTensor.from_*` "
                        "functions instead.")

    cdef void init(self, const shared_ptr[CSparseCSFTensor]& sp_sparse_tensor):
        self.sp_sparse_tensor = sp_sparse_tensor
        self.stp = sp_sparse_tensor.get()
        self.type = pyarrow_wrap_data_type(self.stp.type())

    def __repr__(self):
        return """<pyarrow.SparseCSFTensor>
type: {0.type}
shape: {0.shape}""".format(self)

    @classmethod
    def from_dense_numpy(cls, obj, dim_names=None):
        """
        Convert numpy.ndarray to arrow::SparseCSFTensor
        """
        return cls.from_tensor(Tensor.from_numpy(obj, dim_names=dim_names))

    @staticmethod
    def from_numpy(data, indptr, indices, shape, axis_order=None,
                   dim_names=None):
        """
        Create arrow::SparseCSFTensor from numpy.ndarrays

        Parameters
        ----------
        data : numpy.ndarray
            Data used to populate the sparse tensor.
        indptr : numpy.ndarray
            The sparsity structure.
            Each two consecutive dimensions in a tensor correspond to
            a buffer in indices.
            A pair of consecutive values at `indptr[dim][i]`
            `indptr[dim][i + 1]` signify a range of nodes in
            `indices[dim + 1]` who are children of `indices[dim][i]` node.
        indices : numpy.ndarray
            Stores values of nodes.
            Each tensor dimension corresponds to a buffer in indptr.
        shape : tuple
            Shape of the matrix.
        axis_order : list, optional
            the sequence in which dimensions were traversed to
            produce the prefix tree.
        dim_names : list, optional
            Names of the dimensions.
        """
        cdef shared_ptr[CSparseCSFTensor] csparse_tensor
        cdef vector[int64_t] c_axis_order
        cdef vector[int64_t] c_shape
        cdef vector[c_string] c_dim_names

        for x in shape:
            c_shape.push_back(x)
        if not axis_order:
            axis_order = np.argsort(shape)
        for x in axis_order:
            c_axis_order.push_back(x)
        if dim_names is not None:
            for x in dim_names:
                c_dim_names.push_back(tobytes(x))

        # Enforce preconditions for SparseCSFTensor indices
        if not (isinstance(indptr, (list, tuple)) and
                isinstance(indices, (list, tuple))):
            raise TypeError("Expected list or tuple, got {}, {}"
                            .format(type(indptr), type(indices)))
        if len(indptr) != len(shape) - 1:
            raise ValueError("Expected list of {ndim} np.arrays for "
                             "SparseCSFTensor.indptr".format(ndim=len(shape)))
        if len(indices) != len(shape):
            raise ValueError("Expected list of {ndim} np.arrays for "
                             "SparseCSFTensor.indices".format(ndim=len(shape)))
        if any([x.ndim != 1 for x in indptr]):
            raise ValueError("Expected a list of 1-dimensional arrays for "
                             "SparseCSFTensor.indptr")
        if any([x.ndim != 1 for x in indices]):
            raise ValueError("Expected a list of 1-dimensional arrays for "
                             "SparseCSFTensor.indices")
        indptr = [np.require(arr, dtype='i8') for arr in indptr]
        indices = [np.require(arr, dtype='i8') for arr in indices]

        check_status(NdarraysToSparseCSFTensor(c_default_memory_pool(), data,
                                               indptr, indices, c_shape,
                                               c_axis_order, c_dim_names,
                                               &csparse_tensor))
        return pyarrow_wrap_sparse_csf_tensor(csparse_tensor)

    @staticmethod
    def from_tensor(obj):
        """
        Convert arrow::Tensor to arrow::SparseCSFTensor

        Parameters
        ----------
        obj : Tensor
            The dense tensor that should be converted.
        """
        cdef shared_ptr[CSparseCSFTensor] csparse_tensor
        cdef shared_ptr[CTensor] ctensor = pyarrow_unwrap_tensor(obj)

        with nogil:
            check_status(TensorToSparseCSFTensor(ctensor, &csparse_tensor))

        return pyarrow_wrap_sparse_csf_tensor(csparse_tensor)

    def to_numpy(self):
        """
        Convert arrow::SparseCSFTensor to numpy.ndarrays with zero copy
        """
        cdef PyObject* out_data
        cdef PyObject* out_indptr
        cdef PyObject* out_indices

        check_status(SparseCSFTensorToNdarray(self.sp_sparse_tensor, self,
                                              &out_data, &out_indptr,
                                              &out_indices))
        return (PyObject_to_object(out_data), PyObject_to_object(out_indptr),
                PyObject_to_object(out_indices))

    def to_tensor(self):
        """
        Convert arrow::SparseCSFTensor to arrow::Tensor
        """

        cdef shared_ptr[CTensor] ctensor
        with nogil:
            ctensor = GetResultValue(self.stp.ToTensor())

        return pyarrow_wrap_tensor(ctensor)

    def equals(self, SparseCSFTensor other):
        """
        Return true if sparse tensors contains exactly equal data
        """
        return self.stp.Equals(deref(other.stp))

    def __eq__(self, other):
        if isinstance(other, SparseCSFTensor):
            return self.equals(other)
        else:
            return NotImplemented

    @property
    def is_mutable(self):
        return self.stp.is_mutable()

    @property
    def ndim(self):
        return self.stp.ndim()

    @property
    def shape(self):
        # Cython knows how to convert a vector[T] to a Python list
        return tuple(self.stp.shape())

    @property
    def size(self):
        return self.stp.size()

    def dim_name(self, i):
        return frombytes(self.stp.dim_name(i))

    @property
    def dim_names(self):
        return tuple(frombytes(x) for x in tuple(self.stp.dim_names()))

    @property
    def non_zero_length(self):
        return self.stp.non_zero_length()