[R] identify.hclust() doesn't cut tree at the vertical position of the mouse pointer

[WATSON Mick]

Dear All

According to the identify.hclust documentation the function "cuts the tree at the vertical position of the pointer and highlights the cluster containing the horizontal position of the pointer".

When I carry out this, the tree isn't cut where I click - in fact, there seems to be a limit below which I cannot go.

Consider the following code:

mat <- matrix(rnorm(5000), ncol=5)
hc <- hclust(dist(mat))
plot(hc)
identify(hc)

No matter where I click on the tree, I cannot cut below around about 5.   I can cut above that value, but not below.

Any help is much appreciated.

> sessionInfo()
R version 2.15.1 (2012-06-22)
Platform: x86_64-pc-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=English_United Kingdom.1252  LC_CTYPE=English_United Kingdom.1252    LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C                           
[5] LC_TIME=English_United Kingdom.1252    

attached base packages:
[1] grid      stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
 [1] geneplotter_1.34.0   lattice_0.20-6       annotate_1.34.1      AnnotationDbi_1.18.1 Biobase_2.16.0       BiocGenerics_0.2.0   BiocInstaller_1.4.7  gplots_2.11.0        MASS_7.3-18         
[10] KernSmooth_2.23-7    caTools_1.13         bitops_1.0-4.1       gdata_2.11.0         gtools_2.7.0        

loaded via a namespace (and not attached):
[1] DBI_0.2-5          IRanges_1.14.4     RColorBrewer_1.0-5 RSQLite_0.11.1     stats4_2.15.1      tools_2.15.1       XML_3.9-4.1        xtable_1.7-0      

Thanks
Mick

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