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java.lang.Objectuk.ac.starlink.table.join.SphericalPolarMatchEngine
public class SphericalPolarMatchEngine
Match engine which works with tuples representing RA, Dec and range.
Each tuple must be a 3-element array of Number
objects:
first element is Right Ascension in radians,
second element is Declination in radians,
third element is range (units are arbitrary, but will be the same as
the error supplied in the constructor).
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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SphericalPolarMatchEngine(double err)
Constructs a new match engine which will match on differences not greater than a given number err, in the same units that the range part of the tuples is specified. |
Method Summary | |
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boolean |
canBoundMatch()
Returns false. |
java.lang.Object[] |
getBins(java.lang.Object[] tuple)
Returns a set of keys for bins into which possible matches for a given tuple might fall. |
java.lang.Comparable[][] |
getMatchBounds(java.lang.Comparable[] min,
java.lang.Comparable[] max)
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. |
DescribedValue[] |
getTuningParameters()
Returns a set of DescribedValue objects whose values can be modified to tune the performance of the match. |
ValueInfo[] |
getTupleInfos()
Returns a set of ValueInfo objects indicating what is required for the elements of each tuple. |
double |
matchScore(java.lang.Object[] tuple1,
java.lang.Object[] tuple2)
Indicates whether two tuples count as matching each other, and if so how closely. |
java.lang.String |
toString()
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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 SphericalPolarMatchEngine(double err)
err
- maximum separation for a matchMethod Detail |
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public DescribedValue[] getTuningParameters()
MatchEngine
DescribedValue.setValue(java.lang.Object)
on the
returned objects.
Changing these values will make no difference to the output of
MatchEngine.matchScore(java.lang.Object[], java.lang.Object[])
, but may change the output of MatchEngine.getBins(java.lang.Object[])
.
This may change the CPU and memory requirements of the match,
but will not change the result. The default value should be
something sensible, so that setting the value of these parameters
is not in general required.
getTuningParameters
in interface MatchEngine
public double matchScore(java.lang.Object[] tuple1, java.lang.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.
matchScore
in interface MatchEngine
tuple1
- one tupletuple2
- the other tuple
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.
getMatchScoreInfo
in interface MatchEngine
public java.lang.Object[] getBins(java.lang.Object[] tuple)
MatchEngine
getBins
in interface MatchEngine
tuple
- tuple
public ValueInfo[] getTupleInfos()
MatchEngine
getTupleInfos
in interface MatchEngine
public DescribedValue[] getMatchParameters()
MatchEngine
DescribedValue.setValue(java.lang.Object)
on the
returned objects.
getMatchParameters
in interface MatchEngine
public boolean canBoundMatch()
canBoundMatch
in interface MatchEngine
public java.lang.Comparable[][] getMatchBounds(java.lang.Comparable[] min, java.lang.Comparable[] max)
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.
getMatchBounds
in interface MatchEngine
min
- 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)max
- 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 java.lang.String toString()
toString
in class java.lang.Object
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Copyright © 2004 CLRC: Central Laboratory of the Research Councils. All rights reserved. | ||||||||
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