Package org.flag4j.operations.sparse.coo

Class SparseElementSearch

java.lang.Object

org.flag4j.operations.sparse.coo.SparseElementSearch

public class SparseElementSearch
extends Object

This class provides methods for efficiently finding if a sparse vector, matrix, or tensor contains a non-zero item at a specified index.

Constructor Summary

Constructors

Constructor	Description
SparseElementSearch()

Method Summary

Modifier and Type	Method	Description
static int	matrixBinarySearch(int[] rowIndices, int[] colIndices, int rowKey, int colKey)	Preforms a binary search along the row and column indices of the non-zero values of a sparse matrix for the location of an entry with the specified target indices.
static int[]	matrixFindRowStartEnd(int[] rowIndices, int rowKey)	Finds the indices of the first and last non-zero element in the specified row of a sparse matrix.

Methods inherited from class java.lang.Object

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

Constructor Details

SparseElementSearch

public SparseElementSearch()

Method Details

matrixBinarySearch

public static int matrixBinarySearch(int[] rowIndices,
 int[] colIndices,
 int rowKey,
 int colKey)

Preforms a binary search along the row and column indices of the non-zero values of a sparse matrix for the location of an entry with the specified target indices.

Parameters:

rowIndices - Row indices of the matrix to search within.

colIndices - Column indices of the matrix to search within.

rowKey - Target row index.

colKey - Target col index.

Returns:

The location of the non-zero element (within the non-zero values array of src) with the specified row and column indices. If this value does not exist, then (-(insertion point) - 1) will be returned. The insertion point is defined as the point at which the value, with the row and column key, would be inserted into the array: the index of the first element greater than the key, or src.entries.length if all elements in the array are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.

matrixFindRowStartEnd

public static int[] matrixFindRowStartEnd(int[] rowIndices,
 int rowKey)

Finds the indices of the first and last non-zero element in the specified row of a sparse matrix. If there is no non-zero element in the sparse matrix at the specified row, negative values will be returned.

Parameters:

rowIndices - Row indices of the matrix to search within.

rowKey - Index of the row to search for within the row indices of the src matrix.

Returns:

If it exists, the first and last index of the non-zero element in the sparse matrix which has the specified rowKey as its row index.