/* XXL: The eXtensible and fleXible Library for data processing
Copyright (C) 2000-2011 Prof. Dr. Bernhard Seeger
Head of the Database Research Group
Department of Mathematics and Computer Science
University of Marburg
Germany
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; If not, see <http://www.gnu.org/licenses/>.
http://code.google.com/p/xxl/
*/
package xxl.core.spatial.points;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Arrays;
import xxl.core.functions.AbstractFunction;
import xxl.core.functions.Function;
import xxl.core.io.Convertable;
import xxl.core.util.BitSet;
/**
* A Wrapper for Fixed-Mantissa-Points.
*
* The data is assumed to be inside the unit-cube [0;1)^dim (i.e. 1 is excluded). For this type
* of data we only store the mantissa of the original floating-point. The conversion from
* floating-point to fixed-point and vice-versa is proveded by the methods
* {@link xxl.core.math.Maths#doubleToNormalizedLongBits(double) doubleToNormalizedLongBits} and
* {@link xxl.core.math.Maths#normalizedLongBitsToDouble(long) normalizedLongBitsToDouble}.
* These methods extract the mantissa using bit operations and perform
* necessary shift operations.
*
* The conversion to a fixed point representation is extremely useful to create z-codes and to compute replicate-rectangles.
* The bit-fields can be easily merged to a zCode. The split-lines of the replication process
* correspond exactly to the bits of the mantissa: if a bit is set it corresponds to the "right" partition
* in the current recursion step of the replication process, otherwise it corresponds to the "left" partition.
* There is no "artificial" mapping/computation between floating points and split-lines involved
* to determine partitions.
*
*
* @see xxl.core.spatial.points.Point
* @see xxl.core.spatial.points.Points
* @see xxl.core.spatial.points.AbstractPoint
* @see xxl.core.spatial.points.FloatPoint
*
*/
public class FixedPoint extends AbstractPoint implements Convertable, Cloneable {
/** A factory for FixedPoints.
*/
public static final Function FACTORY = new AbstractFunction(){
public Object invoke(Object point){
return new FixedPoint( (long[]) point );
}
public Object invoke(Object object, Object dim){
return new FixedPoint( ((Integer)dim).intValue() );
}
};
/** The primitive long-point to be wrapped.
*/
protected long[] point;
/** Creates a new FixedPoint.
*
* @param point the primitive long-point to be wrapped.
*/
public FixedPoint(long[] point){
this.point = point;
}
/** Creates a new FixedPoint from the given DoublePoint (the DoublePoint has to be in [0;1)^dim).
*
* @param dp the DoublePoint to use
*/
public FixedPoint(DoublePoint dp){
double[] d = (double[]) dp.getPoint();
long[] np = new long[d.length];
for(int i=0; i<d.length; i++)
np[i] = xxl.core.math.Maths.doubleToNormalizedLongBits( d[i] ); //convert each component to fixed-point representation
this.point = np;
}
/** Creates a new FixedPoint.
* (with coordinates (0,...,0)).
*
* @param dim dimensionality of the point
*/
public FixedPoint(int dim){
this(new long[dim]);
}
/** Creates a new FixedPoint from a NumberPoint<Long>.
*
* @param point the NumberPoint<Long> to be wrapped.
*/
public FixedPoint(NumberPoint<Long> np){
this(np.dimensions());
Long[] arr = (Long[])np.getPoint();
for (int i=0; i<point.length; i++)
point[i] = arr[i];
}
/** Returns a physical copy of this FixedPoint.
*
* @return returns a physical copy of this FixedPoint
*/
@Override
public Object clone(){
return new FixedPoint((long[])point.clone());
}
/** Converts this FixedPoint to a DoublePoint and returns it.
*
* @return returns DoublePoint representation of this FixedPoint
*/
public DoublePoint toDoublePoint(){
double[] d = new double[dimensions()];
for(int i=0; i<d.length; i++)
d[i] = xxl.core.math.Maths.normalizedLongBitsToDouble(point[i]);
return new DoublePoint(d);
}
/** Returns the primitive float-point wrapped by this FixedPoint.
*
* @return returns the primitive float-point wrapped by this FixedPoint
*/
@Override
public Object getPoint(){
return point;
}
/** Returns the dimensionality of this FixedPoint.
*
* @return returns the dimensionality of this FixedPoint
*/
@Override
public int dimensions(){
return point.length;
}
/**
* Reads the state (the attributes) for an object of this class from
* the specified data input and restores the calling object. The state
* of the object before calling <tt>read</tt> will be lost.<br>
* The <tt>read</tt> method must read the values in the same sequence
* and with the same types as were written by <tt>write</tt>.
*
* @param dataInput the stream to read data from in order to restore
* the object.
* @throws IOException if I/O errors occur.
*/
@Override
public void read (DataInput dataInput) throws IOException{
for(int i=0; i< point.length; i++)
point[i] = dataInput.readLong();
}
/**
* Writes the state (the attributes) of the calling object to the
* specified data output. This method should serialize the state of
* this object without calling another <tt>write</tt> method in order
* to prevent recursions.
*
* @param dataOutput the stream to write the state (the attributes) of
* the object to.
* @throws IOException includes any I/O exceptions that may occur.
*/
@Override
public void write (DataOutput dataOutput) throws IOException{
for(int i=0; i< point.length; i++)
dataOutput.writeLong(point[i]);
}
/** Returns the coordinate of this FixedPoint in a given dimension <dim>.
*
* @param dim dimension to get coordinate
* @return returns the coordinate in given dimension
*/
@Override
public double getValue(int dim){
return xxl.core.math.Maths.normalizedLongBitsToDouble(point[dim]);
}
/* (non-Javadoc)
* @see java.lang.Object#equals()
*/
@Override
public boolean equals(Object o) {
FixedPoint p = (FixedPoint)o;
return Arrays.equals(point, p.point);
}
/* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
long c = 0;
for (int i = 0; i < point.length; i++)
c += point[i];
return (int)c%1117;
}
/* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString(){
StringBuffer sb = new StringBuffer("");
for(int i=0; i<point.length; i++){
sb.append( (new BitSet(point[i])).toString2()+"point["+i+"]:\n" );
}
return sb.toString();
}
}