Package org.carrot2.math.matrix

Class MatrixUtils

java.lang.Object
org.carrot2.math.matrix.MatrixUtils
public class MatrixUtils
extends Object
A set of DoubleMatrix2D shorthands and utility methods.

  • Constructor Summary

    Constructors 
    Constructor Description
    MatrixUtils()  

  • Method Summary

    Modifier and Type Method Description
    static double computeOrthogonality​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A)
    Computes the orthogonality of matrix A.
    static double computeSparseness​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A)
    Computers sparseness of matrix A as a fraction of non-zero elements to the total number of elements.
    static double frobeniusNorm​(org.carrot2.math.mahout.matrix.DoubleMatrix2D matrix)
    Calculates the Frobenius norm of a matrix.
    static int[] maxInColumns​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, int[] indices, double[] maxValues)
    Finds the first maximum element in each column of matrix A.
    static int[] maxInColumns​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, int[] indices, double[] maxValues, org.carrot2.math.mahout.function.DoubleFunction transform)  
    static int maxInRow​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, int row)
    Finds the index of the first maximum element in given row of A.
    static int[] minInColumns​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, int[] indices, double[] minValues)
    Finds the first minimum element in each column of matrix A.
    static org.carrot2.math.mahout.matrix.DoubleMatrix2D normalizeColumnL1​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, double[] work)
    Normalizes column vectors of matrix A so that their L1 norm is equal to 1.0.
    static org.carrot2.math.mahout.matrix.DoubleMatrix2D normalizeColumnL2​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, double[] work)
    Normalizes column vectors of matrix A so that their L2 norm (Euclidean distance) is equal to 1.0.
    static org.carrot2.math.mahout.matrix.DoubleMatrix2D normalizeSparseColumnL2​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, double[] work)
    Normalizes column vectors of a sparse matrix A so that their L2 norm (Euclidean distance) is equal to 1.0.
    static org.carrot2.math.mahout.matrix.DoubleMatrix2D sortedRowsView​(org.carrot2.math.mahout.matrix.DoubleMatrix2D matrix, com.carrotsearch.hppc.sorting.IndirectComparator comparator)
    Returns view of the provided matrix with rows permuted according to the order defined by the provided comparator.
    static double[] sumRows​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, double[] sums)
    Calculates the sum of rows of matrix A.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

  • Method Details

    • normalizeColumnL2

      public static org.carrot2.math.mahout.matrix.DoubleMatrix2D normalizeColumnL2​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, double[] work)
      Normalizes column vectors of matrix A so that their L2 norm (Euclidean distance) is equal to 1.0.
      Parameters:
      A - matrix to normalize
      work - a temporary array of A.columns() doubles that will be overwritten with column's original L2 norms. Supply a non-null pointer to avoid continuous allocation/freeing of memory when doing calculations in a loop. If this parameter is null, a new array will be allocated every time this method is called.
      Returns:
      A with length-normalized columns (for convenience only)

    • normalizeSparseColumnL2

      public static org.carrot2.math.mahout.matrix.DoubleMatrix2D normalizeSparseColumnL2​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, double[] work)
      Normalizes column vectors of a sparse matrix A so that their L2 norm (Euclidean distance) is equal to 1.0.
      Parameters:
      A - matrix to normalize
      work - a temporary array of A.columns() doubles that will be overwritten with column's original L2 norms. Supply a non-null pointer to avoid continuous allocation/freeing of memory when doing calculations in a loop. If this parameter is null, a new array will be allocated every time this method is called.
      Returns:
      A with length-normalized columns (for convenience only)

    • normalizeColumnL1

      public static org.carrot2.math.mahout.matrix.DoubleMatrix2D normalizeColumnL1​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, double[] work)
      Normalizes column vectors of matrix A so that their L1 norm is equal to 1.0.
      Parameters:
      A - matrix to normalize
      work - a temporary array of A.columns() doubles that will be overwritten with column's original L1 norms. Supply a non-null pointer to avoid continuous allocation/freeing of memory when doing calculations in a loop. If this parameter is null, a new array will be allocated every time this method is called.
      Returns:
      A with L1-normalized columns (for convenience only)

    • computeOrthogonality

      public static double computeOrthogonality​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A)
      Computes the orthogonality of matrix A. The orthogonality is computed as a sum of k*(k-1)/2 inner products of A's column vectors, k being the number of columns of A, and then normalized to the 0.0 - 1.0 range.
      Parameters:
      A - matrix to compute orthogonality for, must be column length-normalized
      Returns:
      orthogonality of matrix A. 0.0 denotes a perfect orthogonality between every pair of A's column. 1.0 indicates that all columns of A are parallel.

    • computeSparseness

      public static double computeSparseness​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A)
      Computers sparseness of matrix A as a fraction of non-zero elements to the total number of elements.
      Returns:
      sparseness of A, which is a value between 0.0 (all elements are zero) and 1.0 (all elements are non-zero)

    • minInColumns

      public static int[] minInColumns​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, int[] indices, double[] minValues)
      Finds the first minimum element in each column of matrix A. When calculating minimum values for each column this version should perform better than scanning each column separately.
      Parameters:
      indices - an array of A.columns() integers in which indices of the first minimum element will be stored. If this parameter is null a new array will be allocated.
      minValues - an array of A.columns() doubles in which values of each column's minimum elements will be stored. If this parameter is null a new array will be allocated.
      Returns:
      for each column of A the index of the minimum element

    • maxInColumns

      public static int[] maxInColumns​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, int[] indices, double[] maxValues)
      Finds the first maximum element in each column of matrix A. When calculating maximum values for each column this version should perform better than scanning each column separately.
      Parameters:
      indices - an array of A.columns() integers in which indices of the first maximum element will be stored. If this parameter is null a new array will be allocated.
      maxValues - an array of A.columns() doubles in which values of each column's maximum elements will be stored. If this parameter is null a new array will be allocated.
      Returns:
      for each column of A the index of the maximum element

    • maxInColumns

      public static int[] maxInColumns​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, int[] indices, double[] maxValues, org.carrot2.math.mahout.function.DoubleFunction transform)

    • maxInRow

      public static int maxInRow​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, int row)
      Finds the index of the first maximum element in given row of A.
      Parameters:
      A - the matrix to search
      row - the row to search
      Returns:
      index of the first maximum element or -1 if the input matrix is null or has zero size.

    • sumRows

      public static double[] sumRows​(org.carrot2.math.mahout.matrix.DoubleMatrix2D A, double[] sums)
      Calculates the sum of rows of matrix A.
      Parameters:
      sums - an array to store the results. If the array is null or does not match the number of rows in matrix A, a new array will be created.
      Returns:
      sums of rows of A

    • frobeniusNorm

      public static double frobeniusNorm​(org.carrot2.math.mahout.matrix.DoubleMatrix2D matrix)
      Calculates the Frobenius norm of a matrix.
      See Also:
      Frobenius norm

    • sortedRowsView

      public static org.carrot2.math.mahout.matrix.DoubleMatrix2D sortedRowsView​(org.carrot2.math.mahout.matrix.DoubleMatrix2D matrix, com.carrotsearch.hppc.sorting.IndirectComparator comparator)
      Returns view of the provided matrix with rows permuted according to the order defined by the provided comparator.
      Parameters:
      matrix - to permute
      comparator - to use
      Returns:
      view of the provided matrix with rows permuted according to the order defined by the provided comparator.