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java.lang.Objectuk.ac.starlink.table.join.AbstractSkyMatchEngine
uk.ac.starlink.table.join.FixedSkyMatchEngine
public class FixedSkyMatchEngine
MatchEngine which matches objects on the celestial sphere with a
fixed maximum separation.
The tuples it uses are two-element arrays of Number
objects, representing Right Ascension and Declination respectively
in radians. Other similar longitude/latitude-like coordinate systems
may alternatively be used.
Field Summary |
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Fields inherited from interface uk.ac.starlink.table.join.MatchEngine |
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NO_BINS |
Constructor Summary | |
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FixedSkyMatchEngine(SkyPixellator pixellator,
double separation)
Constructor. |
Method Summary | |
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boolean |
canBoundMatch()
Indicates that the MatchEngine.getMatchBounds(java.lang.Comparable[], java.lang.Comparable[]) method can be invoked
to provide some sort of useful result. |
Object[] |
getBins(Object[] tuple)
Returns a set of keys for bins into which possible matches for a given tuple might fall. |
Comparable[][] |
getMatchBounds(Comparable[] minTuple,
Comparable[] maxTuple)
Given a range of tuple values, returns a range outside which no match to anything within that range can result. |
DescribedValue[] |
getMatchParameters()
Returns a set of DescribedValue objects whose values can be modified to modify the matching criteria. |
ValueInfo |
getMatchScoreInfo()
Returns a description of the value returned by the MatchEngine.matchScore(java.lang.Object[], java.lang.Object[]) method. |
double |
getSeparation()
Returns the maximum separation which corresponds to a match. |
ValueInfo[] |
getTupleInfos()
Returns a set of ValueInfo objects indicating what is required for the elements of each tuple. |
double |
matchScore(Object[] tuple1,
Object[] tuple2)
Indicates whether two tuples count as matching each other, and if so how closely. |
void |
setSeparation(double separation)
Sets the maximum separation which corresponds to a match. |
String |
toString()
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Methods inherited from class uk.ac.starlink.table.join.AbstractSkyMatchEngine |
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calculateSeparation, getScale, getTuningParameters, setScale |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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public FixedSkyMatchEngine(SkyPixellator pixellator, double separation)
pixellator
- handles sky pixellisationseparation
- initial value for maximum match separation,
in radiansMethod Detail |
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public void setSeparation(double separation)
separation
- maximum separation in radianspublic double getSeparation()
public ValueInfo[] getTupleInfos()
MatchEngine
public DescribedValue[] getMatchParameters()
MatchEngine
DescribedValue.setValue(java.lang.Object)
on the
returned objects.
public ValueInfo getMatchScoreInfo()
MatchEngine
MatchEngine.matchScore(java.lang.Object[], java.lang.Object[])
method. The content class should be numeric
(though need not be Double
), and the name,
description and units should be descriptive of whatever the
physical significance of the value is.
If the result of matchScore
is not interesting
(for instance, if it's always either 0 or -1),
null
may be returned.
public double matchScore(Object[] tuple1, Object[] tuple2)
MatchEngine
If there's no reason to do otherwise, the range 0..1 is recommended for successul matches. However, if the result has some sort of physical meaning (such as a distance in real space) that may be used instead.
tuple1
- one tupletuple2
- the other tuple
public Object[] getBins(Object[] tuple)
MatchEngine
tuple
- tuple
public boolean canBoundMatch()
MatchEngine
MatchEngine.getMatchBounds(java.lang.Comparable[], java.lang.Comparable[])
method can be invoked
to provide some sort of useful result.
public Comparable[][] getMatchBounds(Comparable[] minTuple, Comparable[] maxTuple)
MatchEngine
Both the input and output rectangles are specified by tuples representing its opposite corners; equivalently, they are the minimum and maximum values of each tuple element. In either the input or output min/max tuples, any element may be null to indicate that no information is available on the bounds of that tuple element (coordinate).
This method can be used by match algorithms which know in advance the range of coordinates they will match against and wish to reduce workload by not attempting matches which are bound to fail.
For example, a 1-d Cartesian match engine with an isotropic match error 0.5 would turn input values of ((0,200),(10,210)) into output values ((-0.5,199.5),(10.5,210.5)).
This method will only be called if MatchEngine.canBoundMatch()
returns true. Thus engines that cannot provide any useful
information along these lines (for instance because none of its
tuple elements is Comparable
do not need to
implement it in a meaningful way.
minTuple
- tuple consisting of the minimum values of each
tuple element in a possible match
(to put it another way - coordinates of one corner of a
tuple-space rectangle containing such a match)maxTuple
- tuple consisting of the maximum values of each
tuple element in a possible match
(to put it another way - coordinates of the other corner of a
tuple-space rectangle containing such a match)
MatchEngine.canBoundMatch()
public String toString()
toString
in class AbstractSkyMatchEngine
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Copyright © 2004 CLRC: Central Laboratory of the Research Councils. All rights reserved. | ||||||||
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