/**
* Merges the specified date/value point into this builder.
*
* <p>The operator is invoked if the date already exists.
*
* @param date the date to be added
* @param value the value associated with the date
* @param operator the operator to use for merging
* @return this builder
*/
public LocalDateDoubleTimeSeriesBuilder merge(
LocalDate date, double value, DoubleBinaryOperator operator) {
ArgChecker.notNull(date, "date");
ArgChecker.notNull(operator, "operator");
entries.merge(date, value, (a, b) -> operator.applyAsDouble(a, b));
return this;
}
/**
* Reduces this matrix returning a single value.
*
* <p>This is used to reduce the values in this matrix to a single value. The operator is called
* once for each element in the matrix. The first argument to the operator is the running total of
* the reduction, starting from zero. The second argument to the operator is the element.
*
* <p>This instance is immutable and unaffected by this method.
*
* @param identity the identity value to start from
* @param operator the operator used to combine the value with the current total
* @return the result of the reduction
*/
public double reduce(double identity, DoubleBinaryOperator operator) {
double result = identity;
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
result = operator.applyAsDouble(result, array[i][j]);
}
}
return result;
}
/**
* Returns an instance where each element is formed by some combination of the matching values in
* this matrix and the other matrix.
*
* <p>This is used to combine two matrices, returning a new matrix. Element {@code (i,j)} in the
* resulting matrix is equal to the result of the operator when applied to element {@code (i,j)}
* in this array and element {@code (i,j)} in the other array. The arrays must be of the same
* size.
*
* <p>This instance is immutable and unaffected by this method.
*
* @param other the other matrix
* @param operator the operator used to combine each pair of values
* @return a copy of this matrix combined with the specified matrix
* @throws IllegalArgumentException if the matrices have different sizes
*/
public DoubleMatrix combine(DoubleMatrix other, DoubleBinaryOperator operator) {
if (rows != other.rows || columns != other.columns) {
throw new IllegalArgumentException("Arrays have different sizes");
}
double[][] result = new double[rows][columns];
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
result[i][j] = operator.applyAsDouble(array[i][j], other.array[i][j]);
}
}
return new DoubleMatrix(result, rows, columns);
}
/**
* Merges the specified date/value point into this builder.
*
* <p>The operator is invoked if the date already exists.
*
* @param point the point to be added
* @param operator the operator to use for merging
* @return this builder
*/
public LocalDateDoubleTimeSeriesBuilder merge(
LocalDateDoublePoint point, DoubleBinaryOperator operator) {
ArgChecker.notNull(point, "point");
entries.merge(point.getDate(), point.getValue(), (a, b) -> operator.applyAsDouble(a, b));
return this;
}