
MINIMUM SPANNING TREEName:
The minimum spanning tree is the spanning tree for which the sum of the distances over the edges in the spanning tree is a minimum. Dataplot supports two forms of the minimum spanning tree.
<SUBSET/EXPCEPT/FOR qualification> where <y> is a variable containing the ycoordinates of the full data set; <x> is a variable containing the xcoordinates of the full data set; <y2> is a variable that will contain the ycoordinats of the returned minimum spanning tree; <x2> is a variable that will contain the xcoordinats of the returned minimum spanning tree; <tag> is a variable that will contain a traceid (i.e., points that will be connected) of the returned minimum spanning tree; and where the <SUBSET/EXCEPT/FOR qualification> is optional.
<SUBSET/EXPCEPT/FOR qualification> where <dist> is a matrix containing the distances (or weights or costs); <edge1> is a variable that will contain the first vertex of the edges in the mimimum spanning tree; <edge2> is a variable that will contain the second vertex of the edges in the mimimum spanning tree; and where the <SUBSET/EXCEPT/FOR qualification> is optional.
LET EDGE1 EDGE2 = MINIMUM SPANNING TREE DIST
read matrix d 0 100 125 120 110 100 0 40 65 60 125 40 0 45 55 120 65 45 0 50 110 60 55 50 0 end of data . let y2 x2 = minimum spanning tree d set write decimals 1 print y2 x2The following output is generated. 2 1 3 2 4 3 5 4Program 2: skip 1 read convex_hull.dat x y . let y2 x2 tag = minimum spanning tree y x . title case asis title offset 2 title Minimum Spanning Tree y1label Y x1label X tic offset units screen tic offset 3 3 x3label . plot y2 x2 tag
Date created: 1/26/2009 