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

[Uwe Ligges]

Paul Hewson wrote:

> 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.


   pairs(dummy.data,
     lower.panel = function(x, y) points(x, y, pch = levels(gender)))

Uwe Ligges



> 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
> 
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