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7.1.6 1d, 2d, ...: Isotropic Cartesian Matching

matcher=1d values*='<x>'
           params='<error>'
           tuning='<bin-factor>'
values*:
  • x: Cartesian co-ordinate #1
params:
  • error: Maximum Cartesian separation for match
tuning:
  • bin-factor: Scaling factor to adjust bin size; larger values mean larger bins

matcher=2d values*='<x> <y>'
           params='<error>'
           tuning='<bin-factor>'
values*:
  • x: Cartesian co-ordinate #1
  • y: Cartesian co-ordinate #2
params:
  • error: Maximum Cartesian separation for match
tuning:
  • bin-factor: Scaling factor to adjust bin size; larger values mean larger bins

The 1d matcher compares positions in 1-dimensional Cartesian space. Rows are considered to match if their x column values differ by no more than error.

The 2d matcher compares postions in 2-dimensional Cartesian space. Rows are considered to match if the difference in their (x,y) positions reckoned using Pythagoras is less than error.

Matching in any number of Cartesian dimensions can be done by extending this syntax in the obvious way.


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STILTS - Starlink Tables Infrastructure Library Tool Set
Starlink User Note256
STILTS web page: http://www.starlink.ac.uk/stilts/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk