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124 lines
3.2 KiB
124 lines
3.2 KiB
5 years ago
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//========= Copyright Valve Corporation, All rights reserved. ============//
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//
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// Purpose:
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//
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// A class allowing storage of a sparse NxN matirx as an array of sparse rows
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//===========================================================================//
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#ifndef SPARSEMATRIX_H
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#define SPARSEMATRIX_H
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#include "tier1/utlvector.h"
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/// CSparseMatrix is a matrix which compresses each row individually, not storing the zeros. NOte,
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/// that while you can randomly set any element in a CSparseMatrix, you really want to do it top to
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/// bottom or you will have bad perf as data is moved around to insert new elements.
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class CSparseMatrix
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{
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public:
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struct NonZeroValueDescriptor_t
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{
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int m_nColumnNumber;
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float m_flValue;
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};
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struct RowDescriptor_t
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{
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int m_nNonZeroCount; // number of non-zero elements in the row
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int m_nDataIndex; // index of NonZeroValueDescriptor_t for the first non-zero value
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};
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int m_nNumRows;
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int m_nNumCols;
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CUtlVector<RowDescriptor_t> m_rowDescriptors;
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CUtlVector<NonZeroValueDescriptor_t> m_entries;
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int m_nHighestRowAppendedTo;
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void AdjustAllRowIndicesAfter( int nStartRow, int nDelta );
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public:
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FORCEINLINE float Element( int nRow, int nCol ) const;
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void SetElement( int nRow, int nCol, float flValue );
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void SetDimensions( int nNumRows, int nNumCols );
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void AppendElement( int nRow, int nCol, float flValue );
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void FinishedAppending( void );
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FORCEINLINE int Height( void ) const { return m_nNumRows; }
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FORCEINLINE int Width( void ) const { return m_nNumCols; }
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};
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FORCEINLINE float CSparseMatrix::Element( int nRow, int nCol ) const
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{
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Assert( nCol < m_nNumCols );
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int nCount = m_rowDescriptors[nRow].m_nNonZeroCount;
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if ( nCount )
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{
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NonZeroValueDescriptor_t const *pValue = &(m_entries[m_rowDescriptors[nRow].m_nDataIndex]);
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do
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{
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int nIdx = pValue->m_nColumnNumber;
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if ( nIdx == nCol )
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{
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return pValue->m_flValue;
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}
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if ( nIdx > nCol )
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{
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break;
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}
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pValue++;
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} while( --nCount );
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}
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return 0;
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}
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// type-specific overrides of matrixmath template for special case sparse routines
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namespace MatrixMath
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{
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/// sparse * dense matrix x matrix multiplication
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template<class BTYPE, class OUTTYPE>
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void MatrixMultiply( CSparseMatrix const &matA, BTYPE const &matB, OUTTYPE *pMatrixOut )
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{
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Assert( matA.Width() == matB.Height() );
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pMatrixOut->SetDimensions( matA.Height(), matB.Width() );
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for( int i = 0; i < matA.Height(); i++ )
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{
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for( int j = 0; j < matB.Width(); j++ )
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{
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// compute inner product efficiently because of sparsity
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int nCnt = matA.m_rowDescriptors[i].m_nNonZeroCount;
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int nDataIdx = matA.m_rowDescriptors[i].m_nDataIndex;
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float flDot = 0.0;
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for( int nIdx = 0; nIdx < nCnt; nIdx++ )
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{
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float flAValue = matA.m_entries[nIdx + nDataIdx].m_flValue;
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int nCol = matA.m_entries[nIdx + nDataIdx].m_nColumnNumber;
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flDot += flAValue * matB.Element( nCol, j );
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}
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pMatrixOut->SetElement( i, j, flDot );
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}
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}
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}
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FORCEINLINE void AppendElement( CSparseMatrix &matrix, int nRow, int nCol, float flValue )
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{
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matrix.AppendElement( nRow, nCol, flValue ); // default implementation
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}
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FORCEINLINE void FinishedAppending( CSparseMatrix &matrix )
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{
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matrix.FinishedAppending();
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}
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};
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#endif // SPARSEMATRIX_H
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