Class CsrConversions

java.lang.Object

org.flag4j.linalg.ops.sparse.csr.CsrConversions

public final class CsrConversions
extends Object

Utility class for converting CSR matrices to flat matrices, dense matrices, etc.

Method Summary

Modifier and Type	Method	Description
static <T> Shape	flatten(Shape shape, T[] entries, int[] rowPointers, int[] colIndices, int axis, int[] destRowPointers, int[] destColIndices)	Computes the new row pointers and column indices for a sparse CSR matrix flattened along some axis.
static <T> void	toCoo(Shape shape, T[] entries, int[] rowPointers, int[] colIndices, T[] destEntries, int[] destRowIndices, int[] destColIndices)	Converts a sparse CSR matrix to an equivalent sparse COO matrix.
static <T> void	toDense(Shape shape, T[] entries, int[] rowPointers, int[] colIndices, T[] dest, T zero)	Converts a sparse CSR matrix to a dense matrix.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

flatten

public static <T> Shape flatten(Shape shape,
 T[] entries,
 int[] rowPointers,
 int[] colIndices,
 int axis,
 int[] destRowPointers,
 int[] destColIndices)

Computes the new row pointers and column indices for a sparse CSR matrix flattened along some axis.

Parameters:

shape - Shape of the CSR matrix to be flattened.

entries - Non-zero data of the CSR matrix.

rowPointers - Non-zero row pointers of the CSR matrix.

colIndices - Non-zero column indices of the CSR matrix.

axis - Axis along which to flatten matrix. Must be 0 or 1.

• If axis==0 then the matrix will be flattened to a single row.
• If axis==1 then the matrix will be flattened to a single column.

destRowPointers - Array to store the non-zero row pointers resulting from flattening the CSR matrix along the specified axis.

destColIndices - Array to store the non-zero column indices resulting from flattening the CSR matrix along the specified axis.

Returns:

The shape of the flattened matrix.

Throws:

LinearAlgebraException - If axis != 0 || axis != 1.

toDense

public static <T> void toDense(Shape shape,
 T[] entries,
 int[] rowPointers,
 int[] colIndices,
 T[] dest,
 T zero)

Converts a sparse CSR matrix to a dense matrix.

Parameters:

shape - Shape of the CSR matrix. Must be rank 2.

entries - Non-zero data of the CSR matrix.

rowPointers - Non-zero row pointers of the CSR matrix.

colIndices - Non-zero column indices of the CSR matrix.

dest - Array to store the dense result in.

zero - Zero element to fill zero value of the sparse matrix with.

Throws:

IllegalArgumentException - If dest.length < shape.totalEntriesIntValueExact()

toCoo

public static <T> void toCoo(Shape shape,
 T[] entries,
 int[] rowPointers,
 int[] colIndices,
 T[] destEntries,
 int[] destRowIndices,
 int[] destColIndices)

Converts a sparse CSR matrix to an equivalent sparse COO matrix.

Parameters:

shape - Shape of the CSR matrix.

entries - Non-zero data of the CSR matrix.

rowPointers - Non-zero row pointers of the CSR matrix.

colIndices - Non-zero column indices of the CSR matrix.

destEntries - Array to store the non-zero data of the COO matrix.

destColIndices - Array to store the non-zero column indices of the COO matrix.

rowIndices - Array to store the non-zero row indices of the COO matrix.