matrix.h

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#ifndef MATRIX_H
#define MATRIX_H
 
#include <QtGlobal>
#include <QString>  //for static const QString declares below
#include <functional>   // std::function, for the optional cancelCheck callback
#include <utility>      // std::pair, std::make_pair
#include <vector>
 
using namespace std; //or else compiler groans for nothrow
 
class QTextStream;
 
 
#ifdef Q_OS_WIN32
static const QString infinity = "\u221E" ;
#else
static const QString infinity = QString("\xE2\x88\x9E") ;
#endif
 
 
static const int METRIC_NONE = -1;
static const int METRIC_SIMPLE_MATCHING  = 0;
static const int METRIC_JACCARD_INDEX = 1;
static const int METRIC_HAMMING_DISTANCE = 2;
static const int METRIC_COSINE_SIMILARITY  = 3;
static const int METRIC_EUCLIDEAN_DISTANCE = 4;
static const int METRIC_MANHATTAN_DISTANCE= 5;
static const int METRIC_PEARSON_COEFFICIENT = 6;
static const int METRIC_CHEBYSHEV_MAXIMUM= 7;
 

 
 
class Matrix {
public:
    Matrix (int rowDim=0, int colDim=0)  ;
 
    Matrix(const Matrix &b) ;   /* Copy constructor allows Matrix a=b  */
 
    ~Matrix();
 
    void clear();
 
    void resize (const int m, const int n) ;
 
    // m_rowPtr[r] is the address of row r's first cell inside m_data (see rebuildRowPtr()
    // below). So m_rowPtr[r][c] is: fetch that address, then step c cells forward.
    qreal item( int r, int c ) { return m_rowPtr[r][c]; }
 
    void setItem(const int r, const int c, const qreal elem ) { m_rowPtr[r][c] = elem; }
 
    // Returns a raw pointer to the start of row r, so a[i][j] indexing keeps working
    // for ludcmp()/lubksb()/inverse() without a wrapper row type.
    qreal* operator []  (const int &r)  { return m_rowPtr[r]; }
 
    void clearItem( int r, int c ) { m_rowPtr[r][c] = 0; }
 
    int cols() {return m_cols;}
 
    int rows() {return m_rows;}
 
    int  size() { return m_rows * m_cols; }
 
    void findMinMaxValues(qreal&min, qreal&max, bool &hasRealNumbers);
 
    bool hasNegativeEntry();
 
    void NeighboursNearestFarthest(qreal&min,qreal&max,
                          int &imin, int &jmin,
                          int &imax, int &jmax);
 
    void deleteRowColumn(int i);    /* deletes row i and column i */
 
    void identityMatrix (int dim);
 
    void zeroMatrix (const int m, const int n);
 
    void fillMatrix (qreal value );
 
    Matrix& subtractFromI () ;
 
 
    Matrix& operator =(const Matrix & a);
 
    void sum(Matrix &a, Matrix &b) ;
 
    void operator +=(Matrix & b);
 
    Matrix operator +(Matrix & b);
 
    Matrix operator -(Matrix & b);
 
    Matrix operator *(Matrix & b);
    void operator *=(Matrix & b);
 
    void product( Matrix &A, Matrix & B, bool symmetry=false) ;
 
    Matrix & productSym( Matrix &a, Matrix & b)  ;
 
    void swapRows(int rowA,int rowB);
 
    void multiplyScalar(const qreal &f);
    void multiplyRow(int row, qreal value);
 
    void productByVector (
            qreal in[],
            qreal out[],
            const bool &leftMultiply=false);
 
    Matrix pow (int n, bool symmetry=false)  ;
    Matrix expBySquaring2 (Matrix &Y, Matrix &X, int n, bool symmetry=false);
 
    qreal distanceManhattan(
            qreal x[],
            qreal y[],
            int n);
    qreal distanceEuclidean(
            qreal x[],
            int n);
 
    void powerIteration (
            qreal x[] ,
            qreal &xsum,
            qreal &xmax,
            int &xmaxi,
            qreal &xmin,
            int &xmini,
            const qreal eps, const int &maxIter,
            std::function<bool()> cancelCheck = nullptr,
            qreal *lambdaMax = nullptr);
 
    qreal spectralRadiusExact(const qreal eps = 0.0000001, const int maxIter = 500,
                              std::function<bool()> cancelCheck = nullptr);
 
    qreal spectralRadiusBound();
 
    Matrix& degreeMatrix();
 
    Matrix& laplacianMatrix();
 
    Matrix& transpose();
 
    Matrix& cocitationMatrix();
 
 
    Matrix& inverseByGaussJordanElimination(Matrix &a);
 
    bool inverse(Matrix &a, std::function<bool()> cancelCheck = nullptr);
 
    bool solve(qreal b[]);
 
    bool ludcmp (Matrix &a, const int &n, int indx[], qreal &d, std::function<bool()> cancelCheck = nullptr) ;
 
    void lubksb (Matrix &a, const int &n, int indx[], qreal b[]);
 
 
    Matrix& distancesMatrix(const int &metric,
                            const QString varLocation,
                            const bool &diagonal,
                            const bool &considerWeights,
                            std::function<bool()> cancelCheck = nullptr);
 
    Matrix& similarityMatrix(Matrix &AM,
                               const int &measure,
                               const QString varLocation="Rows",
                               const bool &diagonal=false,
                               const bool &considerWeights=true,
                               std::function<bool()> cancelCheck = nullptr);
 
 
    Matrix& pearsonCorrelationCoefficients(Matrix &AM,
                                          const QString &varLocation="Rows",
                                           const bool &diagonal=false,
                                           std::function<bool()> cancelCheck = nullptr);
 
 
    friend QTextStream& operator <<  (QTextStream& os, Matrix& m);
    bool printHTMLTable(QTextStream& os,
                        const bool markDiag=false,
                        const bool &plain=false,
                        const bool &printInfinity=true);
    bool printMatrixConsole(bool debug=true);
 
    bool illDefined();
 
private:
    // Builds m_rowPtr[]: a lookup table of row-start pointers into m_data, one entry per
    // row, so item()/setItem()/operator[] never have to recompute a row's address from
    // scratch. Concretely: m_rowPtr is an array of m_rows pointers; entry r is set to
    // "m_data, advanced by r whole rows" (r*m_cols cells). Looking up cell (r,c) then
    // becomes "read m_rowPtr[r] to get row r's address, then step c cells forward from
    // it" - one array read plus one cheap offset, regardless of how large the matrix is,
    // versus recomputing r*m_cols (a real multiplication) on every single access.
    //
    // Must be called once after every place that gives m_data a new address or a new
    // m_cols - the constructor, the copy constructor, resize(), identityMatrix(),
    // zeroMatrix(), deleteRowColumn(), and the branch of operator=() that reallocates -
    // because every entry in the old m_rowPtr[] would otherwise point at stale memory or
    // use the wrong row width. Complexity: O(m_rows) - one pointer computed per row, not
    // per cell, which is what keeps this cheap even for large matrices.
    //
    // This function only allocates and fills; it does not free a previous m_rowPtr array.
    // Callers that already have one from an earlier allocation must free it themselves
    // first (via clear(), or a direct delete[] - see deleteRowColumn()) before calling this.
    void rebuildRowPtr() {
        m_rowPtr = new (nothrow) qreal*[m_rows];
        Q_CHECK_PTR( m_rowPtr );
        for (int i=0; i<m_rows; i++) {
            m_rowPtr[i] = m_data + static_cast<size_t>(i) * m_cols;
        }
    }
 
    qreal *m_data;   // the actual N*M cells, one allocation, row-major.
    qreal **m_rowPtr; // m_rowPtr[r] == m_data + r*m_cols, precomputed for every row.
    int m_rows;
    int m_cols;
 
};
 
 
 
 
 
#endif