[R] plot.hclust: strange behaviour with "manufactured" hclust object

[Hugh Chipman]

I've been trying to get plot.hclust to work with a hclust object I
created and have not had much success.  It seems that there is some
"hidden" characteristic of a hclust object that I can't see.  This is
most easily seen in the following example, where plot.hclust works on
one object, but when this object is "dumped" and then re-read,
plot.hclust no longer works.  Is this a scoping problem?

Script started on Wed Feb 20 13:17:37 2002
1>@icarus[101]% R

R : Copyright 2002, The R Development Core Team
Version 1.4.1  (2002-01-30)

......(stuff deleted)

> set.seed(103)
> library(mva)
> x <- matrix(rnorm(5*2),ncol=2)
> x.hc <- hclust(dist(x),method='average')     
> plot.hclust(x.hc)
# the above works

> dump('x.hc')
> source('dumpdata.R')
> plot.hclust(x.hc)
Error in plot.hclust(x.hc) : invalid dendrogram input

One hypothesis I had was that it might be something like the "call"
object that wasn't correctly being re-created by the dump & source,
but that doesn't seem to be it.  Below, I remove everything except
merge, order, and height, and plot.hclust still works on the original
object and fails on the dump + source object.

> x.hc <- hclust(dist(x),method='average')
> x.hc$call <- NULL
> x.hc$dist.method <- NULL
> x.hc$method <- NULL
> x.hc$labels <- NULL
> plot.hclust(x.hc)
> dump('x.hc')
> source('dumpdata.R')
> plot.hclust(x.hc)
Error in plot.hclust(x.hc) : invalid dendrogram input
> 
> str(x.hc)
List of 3
 $ merge : num [1:4, 1:2] -2 -5 -1 -4 -3 1 2 3
 $ height: num [1:4] 0.873 1.257 1.633 2.430
 $ order : num [1:5] 4 1 5 2 3
 - attr(*, "class")= chr "hclust"

Any help would be greatly appreciated!

Hugh Chipman

-- 
-- Hugh Chipman -- Associate Professor, Statistics & Actuarial Science --
-- University of Waterloo, Ontario, Canada                             --
--                                                                     --
-- Visiting Stanford Statistics Department, January-March 2002         --
-- (650) 725 6148                                   Fax (650) 725-8977 --
-- Department of Statistics, Sequoia Hall, 390 Serra Mall              --
-- Stanford University, Stanford, CA 94305-4065                        --
-- http://www.stats.uwaterloo.ca/~hachipma/     hachipman at uwaterloo.ca --
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._