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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN"><html><head><title>SOM Toolbox / som_neighborhood </title></head><body bgcolor=#f0f0f0><table border=0 width="100%" cellpadding=0 cellspacing=0><tr><td valign=baseline><font size=+2>SOM Toolbox</font></td><td valign=baseline align=center><a href="somtoolbox.html">Online documentation</td><td valign=baseline align=right><a href="http://www.cis.hut.fi/projects/somtoolbox/" target="_top">http://www.cis.hut.fi/projects/somtoolbox/</a></td></tr></table><hr><H1> som_neighborhood </H1><H3> Purpose </H3><PRE> Calculate to which neighborhood each map unit belongs to relative to each other map unit, given the units in 1-neighborhood of each unit.</PRE><H3> Syntax </H3><UL><PRE> Ne = som_neighborhood(Ne1); Ne = som_neighborhood(Ne1,n);</PRE></UL><H3> Description </H3><PRE> For each map unit, finds the minimum neighborhood to which it belongs to relative to each other map unit. Or, equivalently, for each map unit, finds which units form its k-neighborhood, where k goes from 0 to n. The neighborhood is calculated iteratively using the reflexivity of neighborhood. let N1i be the 1-neighborhood set a unit i and let N11i be the set of units in the 1-neighborhood of any unit j in N1i then N2i (the 2-neighborhood set of unit i) is N11i \ N1i Consider, for example, the case of a 5x5 map. The neighborhood in case of 'rect' and 'hexa' lattices (and 'sheet' shape) for the unit at the center of the map are depicted below: 'rect' lattice 'hexa' lattice -------------- -------------- 4 3 2 3 4 3 2 2 2 3 3 2 1 2 3 2 1 1 2 3 2 1 0 1 2 2 1 0 1 2 3 2 1 2 3 2 1 1 2 3 4 3 2 3 4 3 2 2 2 3 Because the iterative procedure is rather slow, the neighborhoods are calculated upto given maximal value. The uncalculated values in the returned matrix are Inf:s.</PRE><H3> Required input arguments </H3><PRE> Ne1 (matrix) Each row contains 1, if the corresponding unit is adjacent for that map unit, 0 otherwise. This can be calculated using SOM_UNIT_NEIGHS. The matrix can be sparse. Size munits x munits.</PRE><H3> Optional input arguments </H3><PRE> n (scalar) Maximal neighborhood value which is calculated, Inf by default (all neighborhoods).</PRE><H3> Output arguments </H3><PRE> Ne (matrix) neighborhood values for each map unit, size is [munits, munits]. The matrix contains the minimum neighborhood of unit i, to which unit j belongs, or Inf, if the neighborhood was bigger than n.</PRE><H3> Examples </H3><PRE> Ne = som_neighborhood(Ne1,1); % upto 1-neighborhood Ne = som_neighborhood(Ne1,Inf); % all neighborhoods Ne = som_neighborhood(som_unit_neighs(topol),4);</PRE><H3> See also </H3><TABLE NOBORDER WIDTH=80%><TR><TD><a href="som_unit_neighs.html"><B>som_unit_neighs</B></a><TD> Calculate units in 1-neighborhood for each map unit.<TR><TD><a href="som_unit_coords.html"><B>som_unit_coords</B></a><TD> Calculate grid coordinates.<TR><TD><a href="som_unit_dists.html"><B>som_unit_dists</B></a><TD> Calculate interunit distances.<TR><TD><a href="som_connection.html"><B>som_connection</B></a><TD> Connection matrix.</TABLE><p><hr><br><br><!-- Last updated: May 30 2002 --></body></html>⌨️ 快捷键说明
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