VariableAxis.java

package hep.aida.ref;

import hep.aida.IAxis;
import hep.aida.IHistogram;
/**
Variable-width axis; A reference implementation of hep.aida.IAxis.

@author Wolfgang Hoschek, Tony Johnson, and others.
@version 1.0, 23/03/2000
*/
public class VariableAxis implements IAxis 
{
	protected double min; 
	protected int bins;
	protected double[] edges;
	/**
	 * Constructs and returns an axis with the given bin edges.
	 * Example: <tt>edges = (0.2, 1.0, 5.0)</tt> yields an axis with 2 in-range bins <tt>[0.2,1.0), [1.0,5.0)</tt> and 2 extra bins <tt>[-inf,0.2), [5.0,inf]</tt>.
	 * @param edges the bin boundaries the partition shall have;
	 *        must be sorted ascending and must not contain multiple identical elements.
	 * @throws IllegalArgumentException if <tt>edges.length < 1</tt>.
	 */
	public VariableAxis(double[] edges) 
	{
		if (edges.length < 1) throw new IllegalArgumentException();

		// check if really sorted and has no multiple identical elements
		for (int i=0; i<edges.length-1; i++) {
			if (edges[i+1] <= edges[i]) {
				throw new IllegalArgumentException("edges must be sorted ascending and must not contain multiple identical values");
			}
		}
			
		this.min = edges[0];
		this.bins = edges.length - 1;
		this.edges = (double[]) edges.clone();
	}
	public double binCentre(int index)
	{
		return (binLowerEdge(index) + binUpperEdge(index)) / 2;
	}
	public double binLowerEdge(int index)
	{
		if (index == IHistogram.UNDERFLOW) return Double.NEGATIVE_INFINITY;
		if (index == IHistogram.OVERFLOW) return upperEdge();
		return edges[index];
	}
	public int bins()
	{
		return bins;
	}
	public double binUpperEdge(int index)
	{
		if (index == IHistogram.UNDERFLOW) return lowerEdge();
		if (index == IHistogram.OVERFLOW) return Double.POSITIVE_INFINITY;
		return edges[index+1];
	}
	public double binWidth(int index)
	{
		return binUpperEdge(index) - binLowerEdge(index);
	}
	public int coordToIndex(double coord)
	{
		if (coord < min) return IHistogram.UNDERFLOW;
		
		int	index = java.util.Arrays.binarySearch(this.edges,coord);
		//int index = new DoubleArrayList(this.edges).binarySearch(coord); // just for debugging
		if (index < 0) index = -index -1-1; // not found
		//else index++; // found

		if (index >= bins) return IHistogram.OVERFLOW;
		
		return index;
	}
	public double lowerEdge()
	{
		return min;
	}
	/**
	 * Returns a string representation of the specified array.  The string
	 * representation consists of a list of the arrays's elements, enclosed in square brackets
	 * (<tt>"[]"</tt>).  Adjacent elements are separated by the characters
	 * <tt>", "</tt> (comma and space).
	 * @return a string representation of the specified array.
	 */
	protected static String toString(double[] array) {
		StringBuffer buf = new StringBuffer();
		buf.append("[");
		int maxIndex = array.length - 1;
		for (int i = 0; i <= maxIndex; i++) {
		    buf.append(array[i]);
		    if (i < maxIndex)
			buf.append(", ");
		}
		buf.append("]");
		return buf.toString();
	}
	public double upperEdge()
	{
		return edges[edges.length-1];
	}
}