[R] Lattice::qqmath -- groups option question
richard.kittler at amd.com
Thu Jun 10 17:38:29 CEST 2004
Thanks for the info. Given that I rule out qqmath would the best method be to make repeated calls to qqnorm without plotting and then overlay the results or is there a more elegant method?
From: Deepayan Sarkar [mailto:deepayan at stat.wisc.edu]
Sent: Thursday, June 10, 2004 7:55 AM
To: r-help at stat.math.ethz.ch
Cc: Kittler, Richard
Subject: Re: [R] Lattice::qqmath -- groups option question
On Thursday 10 June 2004 09:21, richard.kittler at amd.com wrote:
> Does the 'groups' option on qqmath just color the points differently
> in the main distribution or does it actually overlay separate quantile
> plots for each subset? I would like to be able to do the latter.
The 'groups' option doesn't really do anything in any of the high level
lattice functions, it just sends the groups variable (and associated
subscripts) to the panel function. It is the panel function that needs
to know how to deal with that information.
As things stand now, panel.qqmath doesn't know what to do with it. More
importantly, qqmath is currently structured in a way that would make
this very difficult to implement.
I don't think there's a good reason for this (other than consistency
with S-PLUS) and I would prefer to allow the possibility of grouped Q-Q
plots. But this would need a fair bit of restructuring and will
certainly not happen before R 2.0.0.
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