Re: Custom distance function

*To*: mathgroup at smc.vnet.net*Subject*: [mg72108] Re: Custom distance function*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>*Date*: Wed, 13 Dec 2006 06:38:21 -0500 (EST)*Organization*: The Open University, Milton Keynes, UK*References*: <eljbf3$7he$1@smc.vnet.net>

bentheo at gmail.com wrote: > \!\(wcity[A_, B_]\ := \ â??\+\(i = > 1\)\%7\((weights[\([i]\)]*\((Abs[A[\([i]\)] \ > - B[\([i]\)]])\))\)\) > > I was wondering if anyone could lend me a hand with a problem I'm > having. I'm trying to use the standard clusteranalysis package with > Mathematica. Now, I've defined a new distance function, which is > essentially the standard manhattan distance function, but it uses > weights. The function works on lists, and the documentation leads me to > believe it is a legit function, but when I try to use it i get > DistanceMatrix::optx: "Unknown option DistanceFuntion in \ > \!\(DistanceMatrix[{{226.3382425`, 0.286908795`, \[LeftSkeleton]4\ > \[RightSkeleton], 0.742291389`}, \[LeftSkeleton]9\[RightSkeleton], \ > \[LeftSkeleton]3353\[RightSkeleton]}, > \[LeftSkeleton]1\[RightSkeleton]]\). \!\ > \( \*ButtonBox[\(Moreâ?¦\), ButtonData:>\"General::optx\", \ > ButtonStyle->\"RefGuideLinkText\", ButtonFrame->\"None\"]\) > > > Any ideas what I'm doing wrong? > I have just make up an example and your function /wcity/ seems to work fine. (See below.) In[1]:= Needs["Statistics`ClusterAnalysis`"] In[2]:= wcity[A_, B_] := Sum[weights[[i]]* Abs[A[[i]] - B[[i]]], {i, 1, 7}] In[3]:= weights = 1/Range[1, 7] Out[3]= {1, 1/2, 1/3, 1/4, 1/5, 1/6, 1/7} In[4]:= data = Table[Random[Integer, {1, 20}], {10}, {7}] Out[4]= {{10, 1, 5, 11, 4, 1, 18}, {1, 19, 7, 13, 14, 16, 2}, {20, 12, 20, 15, 5, 3, 13}, {19, 6, 4, 17, 10, 7, 19}, {19, 6, 2, 13, 19, 2, 13}, {5, 17, 17, 11, 20, 14, 11}, {19, 14, 18, 14, 4, 5, 1}, {19, 18, 16, 16, 16, 7, 16}, {9, 3, 8, 17, 13, 19, 7}, {15, 7, 6, 16, 18, 19, 5}} In[5]:= FindClusters[data, DistanceFunction -> wcity] Out[5]= {{{10, 1, 5, 11, 4, 1, 18}, {9, 3, 8, 17, 13, 19, 7}, {15, 7, 6, 16, 18, 19, 5}}, {{1, 19, 7, 13, 14, 16, 2}, {5, 17, 17, 11, 20, 14, 11}}, {{20, 12, 20, 15, 5, 3, 13}, {19, 6, 4, 17, 10, 7, 19}, {19, 6, 2, 13, 19, 2, 13}, {19, 14, 18, 14, 4, 5, 1}, {19, 18, 16, 16, 16, 7, 16}}} Regards, Jean-Marc