uk.ac.starlink.table.join
Class HEALPixMatchEngine
java.lang.Object
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+--uk.ac.starlink.table.join.SkyMatchEngine
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+--uk.ac.starlink.table.join.HEALPixMatchEngine
- All Implemented Interfaces:
- MatchEngine
- public class HEALPixMatchEngine
- extends SkyMatchEngine
SkyMatchEngine implementation which works using the HEALPix pixelisation
scheme. This works better than the HTM-based one for two reasons:
- It tends to be much faster to calculate a list of small pixels
in a region, since the calculations are not hierarchical
- The pixels are square which means they generally have fewer
neighbours than triangular HTM ones of a similar size
This implementation is based on the PixTools Java HEALPix classes
written by Nickolai Kouropatkine at Fermilab.
- See Also:
- http://home.fnal.gov/~kuropat/HEALPIX/PixTools.html
Constructor Summary |
HEALPixMatchEngine(double separation)
Constructs a new match engine which considers two points
(RA,Dec tuples) to match if they are within a given angular
distance on the celestial sphere. |
Method Summary |
Object[] |
getBins(Object[] radec)
Returns a set of keys for bins into which possible matches for
a given tuple might fall. |
void |
setSeparation(double separation)
Configures this match engine to consider two points
(RA,Dec tuples) to match if they are within a given angular
distance on the celestial sphere. |
HEALPixMatchEngine
public HEALPixMatchEngine(double separation)
- Constructs a new match engine which considers two points
(RA,Dec tuples) to match if they are within a given angular
distance on the celestial sphere.
- Parameters:
separation
- match radius in radians
setSeparation
public void setSeparation(double separation)
- Description copied from class:
SkyMatchEngine
- Configures this match engine to consider two points
(RA,Dec tuples) to match if they are within a given angular
distance on the celestial sphere.
- Overrides:
setSeparation
in class SkyMatchEngine
- Parameters:
separation
- match radius in radians
getBins
public Object[] getBins(Object[] radec)
- Description copied from interface:
MatchEngine
- Returns a set of keys for bins into which possible matches for
a given tuple might fall.
The returned objects can be anything, but should have their
equals and hashCode methods implemented
properly for comparison.
- Parameters:
radec
- tuple
- Returns:
- set of bin keys which might be returned by invoking this
method on other tuples which count as matches for the
submitted tuple