# [R] Cluster graphs

Stephen R. Laniel laniel at cmu.edu
Fri Oct 1 03:19:41 CEST 1999

```On 10/1/99, 9:42 AM +1000, Michael HART wrote:

> I have a number of items with "distances" of differences between each
> other. What I want to do is to plot each item on a two dimensional plot
> such that the positions on the plot indicate the approximate distance
> between each item.

This doesn't seem like an especially R-related question, but I'll take a
stab at it anyway.  To plot these distances, won't you need to resolve
their positions first?  To resolve their positions, you could use a whole
lot of methods (there's a seminal paper by Householder whose title I can't
remember now -- it's a little paper, but dense).  The important thing to
note is that a collection of distances doesn't uniquely specify a
configuration; if I'm not mistaken, it only specifies configurations up to
rigid motion.  You need to fix a coordinate system and define one of the
points as an origin.

In any event, the whole problem seems beyond the scope of this list, unless
I'm mistaken.

--Steve

Stephen R. Laniel            |    "I've got a match:
Carnegie Mellon University   |     Your embrace and my collapse."
laniel at cmu.edu               |     --They Might Be Giants
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```