Class DoubleArrayMath


  • public final class DoubleArrayMath
    extends java.lang.Object
    Contains utility methods for maths on double arrays.

    This utility is used throughout the system when working with double arrays.

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static double[] apply​(double[] array, java.util.function.DoubleUnaryOperator operator)
      Applies an operator to each element in the array, returning a new array.
      static double[] applyAddition​(double[] array, double valueToAdd)
      Applies an addition to each element in the array, returning a new array.
      static double[] applyMultiplication​(double[] array, double valueToMultiplyBy)
      Applies a multiplication to each element in the array, returning a new array.
      static double[] combine​(double[] array1, double[] array2, java.util.function.DoubleBinaryOperator operator)
      Combines two arrays, returning an array where each element is the combination of the two matching inputs.
      static double[] combineByAddition​(double[] array1, double[] array2)
      Combines two arrays, returning an array where each element is the sum of the two matching inputs.
      static double[] combineByMultiplication​(double[] array1, double[] array2)
      Combines two arrays, returning an array where each element is the multiplication of the two matching inputs.
      static double[] combineLenient​(double[] array1, double[] array2, java.util.function.DoubleBinaryOperator operator)
      Combines two arrays, returning an array where each element is the combination of the two matching inputs.
      static boolean fuzzyEquals​(double[] array1, double[] array2, double tolerance)
      Compares each element in the first array to the matching index in the second array within a tolerance.
      static boolean fuzzyEqualsZero​(double[] array, double tolerance)
      Compares each element in the array to zero within a tolerance.
      static void mutate​(double[] array, java.util.function.DoubleUnaryOperator operator)
      Mutates each element in the array using an operator by mutation.
      static void mutateByAddition​(double[] array, double valueToAdd)
      Adds a constant value to each element in the array by mutation.
      static void mutateByAddition​(double[] array, double[] arrayToAdd)
      Adds values in two arrays together, mutating the first array.
      static void mutateByMultiplication​(double[] array, double valueToMultiplyBy)
      Multiplies each element in the array by a value by mutation.
      static void mutateByMultiplication​(double[] array, double[] arrayToMultiplyBy)
      Multiplies values in two arrays, mutating the first array.
      static void sortPairs​(double[] keys, double[] values)
      Sorts the two arrays, retaining the associated values with the sorted keys.
      static <V> void sortPairs​(double[] keys, V[] values)
      Sorts the two arrays, retaining the associated values with the sorted keys.
      static double sum​(double[] array)
      Calculates the sum total of all the elements in the array.
      static java.lang.Double[] toObject​(double[] array)
      Converts a double array to a Double array.
      static double[] toPrimitive​(java.lang.Double[] array)
      Converts a Double array to a double array.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • EMPTY_DOUBLE_ARRAY

        public static final double[] EMPTY_DOUBLE_ARRAY
        An empty double array.
      • EMPTY_DOUBLE_OBJECT_ARRAY

        public static final java.lang.Double[] EMPTY_DOUBLE_OBJECT_ARRAY
        An empty Double array.
    • Method Detail

      • toObject

        public static java.lang.Double[] toObject​(double[] array)
        Converts a double array to a Double array.
        Parameters:
        array - the array to convert
        Returns:
        the converted array
      • toPrimitive

        public static double[] toPrimitive​(java.lang.Double[] array)
        Converts a Double array to a double array.

        Throws an exception if null is found.

        Parameters:
        array - the array to convert
        Returns:
        the converted array
        Throws:
        java.lang.NullPointerException - if null found
      • sum

        public static double sum​(double[] array)
        Calculates the sum total of all the elements in the array.

        The input array is not mutated.

        Parameters:
        array - the array to sum
        Returns:
        the sum total of all the elements
      • applyAddition

        public static double[] applyAddition​(double[] array,
                                             double valueToAdd)
        Applies an addition to each element in the array, returning a new array.

        The result is always a new array. The input array is not mutated.

        Parameters:
        array - the input array, not mutated
        valueToAdd - the value to add
        Returns:
        the resulting array
      • applyMultiplication

        public static double[] applyMultiplication​(double[] array,
                                                   double valueToMultiplyBy)
        Applies a multiplication to each element in the array, returning a new array.

        The result is always a new array. The input array is not mutated.

        Parameters:
        array - the input array, not mutated
        valueToMultiplyBy - the value to multiply by
        Returns:
        the resulting array
      • apply

        public static double[] apply​(double[] array,
                                     java.util.function.DoubleUnaryOperator operator)
        Applies an operator to each element in the array, returning a new array.

        The result is always a new array. The input array is not mutated.

        Parameters:
        array - the input array, not mutated
        operator - the operator to use
        Returns:
        the resulting array
      • mutateByAddition

        public static void mutateByAddition​(double[] array,
                                            double valueToAdd)
        Adds a constant value to each element in the array by mutation.

        The input array is mutated.

        Parameters:
        array - the array to mutate
        valueToAdd - the value to add
      • mutateByAddition

        public static void mutateByAddition​(double[] array,
                                            double[] arrayToAdd)
        Adds values in two arrays together, mutating the first array.

        The arrays must be the same length. Each value in arrayToAdd is added to the value at the corresponding index in array.

        Parameters:
        array - the array to mutate
        arrayToAdd - the array containing values to add
      • mutateByMultiplication

        public static void mutateByMultiplication​(double[] array,
                                                  double valueToMultiplyBy)
        Multiplies each element in the array by a value by mutation.

        The input array is mutated.

        Parameters:
        array - the array to mutate
        valueToMultiplyBy - the value to multiply by
      • mutateByMultiplication

        public static void mutateByMultiplication​(double[] array,
                                                  double[] arrayToMultiplyBy)
        Multiplies values in two arrays, mutating the first array.

        The arrays must be the same length. Each value in array is multiplied by the value at the corresponding index in arrayToMultiplyBy.

        Parameters:
        array - the array to mutate
        arrayToMultiplyBy - the array containing values to multiply by
      • mutate

        public static void mutate​(double[] array,
                                  java.util.function.DoubleUnaryOperator operator)
        Mutates each element in the array using an operator by mutation.

        The input array is mutated.

        Parameters:
        array - the array to mutate
        operator - the operator to use to perform the mutation
      • combineByAddition

        public static double[] combineByAddition​(double[] array1,
                                                 double[] array2)
        Combines two arrays, returning an array where each element is the sum of the two matching inputs.

        Each element in the result will be the sum of the matching index in the two input arrays. The two input arrays must have the same length.

        For example:

          double[] array1 = {1, 5, 9};
          double[] array2 = {2, 3, 2};
          double[] result = DoubleArrayMath.combineByAddition(array1, array2);
          // result contains {3, 8, 11}
         

        The result is always a new array. The input arrays are not mutated.

        Parameters:
        array1 - the first array
        array2 - the second array
        Returns:
        an array combining the two input arrays using the plus operator
      • combineByMultiplication

        public static double[] combineByMultiplication​(double[] array1,
                                                       double[] array2)
        Combines two arrays, returning an array where each element is the multiplication of the two matching inputs.

        Each element in the result will be the multiplication of the matching index in the two input arrays. The two input arrays must have the same length.

        For example:

          double[] array1 = {1, 5, 9};
          double[] array2 = {2, 3, 4};
          double[] result = DoubleArrayMath.combineByMultiplication(array1, array2);
          // result contains {2, 15, 36}
         

        The result is always a new array. The input arrays are not mutated.

        Parameters:
        array1 - the first array
        array2 - the second array
        Returns:
        an array combining the two input arrays using the multiply operator
      • combine

        public static double[] combine​(double[] array1,
                                       double[] array2,
                                       java.util.function.DoubleBinaryOperator operator)
        Combines two arrays, returning an array where each element is the combination of the two matching inputs.

        Each element in the result will be the combination of the matching index in the two input arrays using the operator. The two input arrays must have the same length.

        The result is always a new array. The input arrays are not mutated.

        Parameters:
        array1 - the first array
        array2 - the second array
        operator - the operator to use when combining values
        Returns:
        an array combining the two input arrays using the operator
      • combineLenient

        public static double[] combineLenient​(double[] array1,
                                              double[] array2,
                                              java.util.function.DoubleBinaryOperator operator)
        Combines two arrays, returning an array where each element is the combination of the two matching inputs.

        Each element in the result will be the combination of the matching index in the two input arrays using the operator. The result will have the length of the longest of the two inputs. Where one array is longer than the other, the values from the longer array will be used.

        The result is always a new array. The input arrays are not mutated.

        Parameters:
        array1 - the first array
        array2 - the second array
        operator - the operator to use when combining values
        Returns:
        an array combining the two input arrays using the operator
      • fuzzyEqualsZero

        public static boolean fuzzyEqualsZero​(double[] array,
                                              double tolerance)
        Compares each element in the array to zero within a tolerance.

        An empty array returns true;

        The input array is not mutated.

        Parameters:
        array - the array to check
        tolerance - the tolerance to use
        Returns:
        true if the array is effectively equal to zero
      • fuzzyEquals

        public static boolean fuzzyEquals​(double[] array1,
                                          double[] array2,
                                          double tolerance)
        Compares each element in the first array to the matching index in the second array within a tolerance.

        If the arrays differ in length, false is returned.

        The input arrays are not mutated.

        Parameters:
        array1 - the first array to check
        array2 - the second array to check
        tolerance - the tolerance to use
        Returns:
        true if the arrays are effectively equal
      • sortPairs

        public static void sortPairs​(double[] keys,
                                     double[] values)
        Sorts the two arrays, retaining the associated values with the sorted keys.

        The two arrays must be the same size and represent a pair of key to value. The sort order is determined by the array of keys. The position of each value is changed to match that of the sorted keys.

        The input arrays are mutated.

        Parameters:
        keys - the array of keys to sort
        values - the array of associated values to retain
      • sortPairs

        public static <V> void sortPairs​(double[] keys,
                                         V[] values)
        Sorts the two arrays, retaining the associated values with the sorted keys.

        The two arrays must be the same size and represent a pair of key to value. The sort order is determined by the array of keys. The position of each value is changed to match that of the sorted keys.

        The input arrays are mutated.

        Type Parameters:
        V - the type of the values
        Parameters:
        keys - the array of keys to sort
        values - the array of associated values to retain