uk.ac.rdg.resc.edal.coverage.grid.impl.AbstractIrregularAxis Maven / Gradle / Ivy
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* Copyright (c) 2012 The University of Reading
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package uk.ac.rdg.resc.edal.coverage.grid.impl;
import java.util.Arrays;
import java.util.List;
import org.opengis.referencing.cs.CoordinateSystemAxis;
import uk.ac.rdg.resc.edal.Extent;
import uk.ac.rdg.resc.edal.position.TimePosition;
import uk.ac.rdg.resc.edal.util.Extents;
/**
* Partial implementation of an irregular axis.
*
* @author Jon
* @author Guy Griffiths
*
* @param
* The type of value the axis contains
*/
public abstract class AbstractIrregularAxis> extends
AbstractReferenceableAxis {
/**
* The axis values, always in ascending numerical order to simplify
* searching
*/
protected T[] axisValues;
/**
* True if axis values in the above array have been reversed
*/
protected boolean reversed;
protected AbstractIrregularAxis(CoordinateSystemAxis coordSysAxis, List axisValues) {
super(coordSysAxis);
init(axisValues);
}
protected AbstractIrregularAxis(String name, List axisValues) {
super(name);
init(axisValues);
}
/**
* Sets all the fields and checks that the axis values ascend or descend
* monotonically, throwing an IllegalArgumentException if not.
*/
private void init(List axisValues) {
if (axisValues.isEmpty()) {
throw new IllegalArgumentException("Zero-length array");
}
if (axisValues.size() == 1) {
@SuppressWarnings("unchecked")
T[] array = axisValues.toArray((T[]) new Comparable[0]);
this.axisValues = array;
return;
}
/*
* This is not recommended behaviour for Java (hence the
* SuppressWarnings), but in this case it is a choice between this,
* unnecessary abstraction, or heavy repetition of code.
*/
@SuppressWarnings("unchecked")
T[] vals = (T[]) new Comparable[axisValues.size()];
this.axisValues = vals;
reversed = axisValues.get(1).compareTo(axisValues.get(0)) < 0;
if (reversed) {
// Reverse the coordinates so that they are in increasing order
for (int i = 0; i < axisValues.size(); i++) {
this.axisValues[i] = axisValues.get(axisValues.size() - 1 - i);
}
} else {
axisValues.toArray(this.axisValues);
}
checkAscending();
}
/**
* Checks that the axis values ascend or descend monotonically, throwing an
* IllegalArgumentException if not.
*/
protected void checkAscending() {
T prevVal = axisValues[0];
for (int i = 1; i < axisValues.length; i++) {
if (axisValues[i].compareTo(prevVal) <= 0) {
throw new IllegalArgumentException(
"Coordinate values must increase or decrease monotonically");
}
prevVal = axisValues[i];
}
}
/*
* If the array has been reversed, we need to reverse the index
*/
private int maybeReverseIndex(int index) {
if (reversed)
return axisValues.length - 1 - index;
else
return index;
}
@Override
public T getCoordinateValue(int index) {
return axisValues[maybeReverseIndex(index)];
}
@Override
public int findIndexOf(T value) {
int index = Arrays.binarySearch(axisValues, value);
if (index >= 0) {
return maybeReverseIndex(index);
} else {
int insertionPoint = -(index + 1);
if (insertionPoint == 0) {
if (getCoordinateBounds(0).contains(value)) {
return maybeReverseIndex(0);
} else {
return -1;
}
}
if (insertionPoint == axisValues.length) {
if (getCoordinateBounds(axisValues.length - 1).contains(value)) {
return maybeReverseIndex(axisValues.length - 1);
} else {
return -1;
}
}
if (Math.abs(difference(axisValues[insertionPoint], value)) < Math.abs(difference(
axisValues[insertionPoint - 1], value))) {
return maybeReverseIndex(insertionPoint);
} else {
return maybeReverseIndex(insertionPoint - 1);
}
}
}
@Override
public int size() {
return axisValues.length;
}
@Override
public boolean isAscending() {
return !reversed;
}
@Override
public Extent getCoordinateBounds(int index) {
int upperIndex = index + 1;
int lowerIndex = index - 1;
T lowerBound;
if (index == 0) {
lowerBound = getCoordinateExtent().getLow();
} else {
lowerBound = getMidpoint(axisValues[index], axisValues[lowerIndex]);
}
T upperBound;
if (index == size() - 1) {
upperBound = getCoordinateExtent().getHigh();
} else {
upperBound = getMidpoint(axisValues[upperIndex], axisValues[index]);
}
return Extents.newExtent(lowerBound, upperBound);
}
/**
* Returns the midpoint of the supplied values. This is so that certain
* methods can be abstracted without worrying about non-trivial midpoint
* calculation (e.g. {@link TimePosition}s)
*
* @param pos1
* the first value
* @param pos2
* the second value
* @return the midpoint of the values
*/
protected abstract T getMidpoint(T pos1, T pos2);
/**
* Returns the difference between the supplied values. This is so that
* certain methods can be abstracted without worrying about non-trivial
* difference calculation (e.g. {@link TimePosition}s)
*
* @param pos1
* the first value
* @param pos2
* the second value
* @return the value corresponding to pos1 - pos2
*/
protected abstract double difference(T pos1, T pos2);
@Override
public int hashCode() {
final int prime = 31;
int result = super.hashCode();
result = prime * result + Arrays.hashCode(axisValues);
result = prime * result + (reversed ? 1231 : 1237);
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (!super.equals(obj))
return false;
if (getClass() != obj.getClass())
return false;
AbstractIrregularAxis other = (AbstractIrregularAxis) obj;
if (!Arrays.equals(axisValues, other.axisValues))
return false;
if (reversed != other.reversed)
return false;
return true;
}
}
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