Class ArrayMath

  • Direct Known Subclasses:
    ArrayMath

    public class ArrayMath
    extends Object
    Utility class for simple vector arithmetic.
    • Constructor Detail

      • ArrayMath

        public ArrayMath()
    • Method Detail

      • innerProduct

        public static double innerProduct​(double[] vecA,
                                          double[] vecB)
      • l1norm

        public static double l1norm​(double[] v)
        L1-norm
      • l2norm

        public static double l2norm​(double[] v)
        L2-norm
      • invL2norm

        public static double invL2norm​(double[] v)
        Inverse L2-norm
      • logSumOfExps

        public static double logSumOfExps​(double[] x)
        Computes \log(\sum_{i=1}^n e^{x_i}) using a maximum-element trick to avoid arithmetic overflow.
        Parameters:
        x - input vector
        Returns:
        log-sum of exponentials of vector elements
      • max

        public static double max​(double[] x)
      • argmax

        public static int argmax​(double[] x)
        Find index of maximum element in the vector x
        Parameters:
        x - input vector
        Returns:
        index of the maximum element. Index of the first maximum element is returned if multiple maximums are found.
      • sumFeatures

        public static void sumFeatures​(Context[] context,
                                       float[] values,
                                       double[] prior)
      • toDoubleArray

        public static double[] toDoubleArray​(List<Double> list)
        Convert a list of Double objects into an array of primitive doubles
      • toIntArray

        public static int[] toIntArray​(List<Integer> list)
        Convert a list of Integer objects into an array of primitive integers