[R] pairs: altering pch options on upper and lower panel of pairwise scatter plots

[Paul Hewson]

Hello,

I can't figure out how to use the upper.panel and lower.panel options in
pairs to alter the label options for either panel independently of the
other.

I would like to be able to show the pairwise scatter plots for the data
as they are (a vanilla pairs plot?) but separately to be able to label
the points according to a factor level.   It is easy enough to do this
independently, but I can't figure out how to combine the two settings on
the same plot.   I have enclosed a toy example:   

Some made up data, e.g.

## make up some multivariate normal data using mvrnorm from MASS
##
require(MASS)
mu <- c(0,0,0)
digma <- matrix(c(0.9,0.5,0.5, 0.5,0.9,0.5, 0.5,0.5,0.9)
dummy.data <- mvrnorm(100,mu,sigma)
##
## add a factor
##
gender <- as.factor(c(rep("Male",50),rep("Female",50)))




I can create two separate pairs plots (upper and lower panel) as
follows:

## pairs plot just showing the data

pairs(dummy.data, lower.panel = NULL)

## pairs plot where the points are labelled according to a factor

pairs(dummy.data, pch = levels(gender), upper.panel = NULL)


But I would like to be able to combine the two panels on the same plot.
I would be grateful for any advice.   I've tried passing several
combinations of functions to upper.panel and lower.panel but either
they're the wrong function or I'm barking up the wrong tree entirely.

Thanks

Paul Hewson

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Lecturer in Statistics
University of Plymouth
Drake Circus 
Plymouth PL4 8AA

Tel ++ 44 1752 232778
Email paul.hewson at plymouth.ac.uk