[Rd] Overriding axis formatting with custom Axis method, Axis.numeric etc

Sklyar, Oleg (MI London) osklyar at maninvestments.com
Mon Apr 7 13:22:36 CEST 2008


Dear list:

I would like to override the default way R formats plot axes with a
custom method(s). Obviously I would prefer to define it as general as
possible avoiding writing a custom method for each individual class
where possible.

The plot.default method (and I assume other methods as well) calls
Axis(...) to produce the axis layout depending on data. In this sense it
seems reasonable to (re)define Axis methods rather than change plot
methods (which are impossible to control as there can be too many custom
ones).

Now my question is how can I redefine Axis that it is automatically
called by plot.default and other plot methods? Or which Axis-method
signatures are already defined that I should redefine?

What I have succeeded so far was defining Axis.numeric and Axis.myClass,
which are called by default if I supply data of class numeric or
myClass. For example, a simple code like

Axis.numeric = AxisFUN = function(x=NULL, at=NULL, ..., side,
labels=TRUE) {
    if (is.null(at)) at = pretty(x)
    axis(at=at, ..., side=side, labels=labels, col="red", lwd=5)
}

run with plot(1:5,1:5) will format both axes red. 

However, if I execute it with plot(1:5) only x axis plotting is
intercepted leaving y at default formatting although it is also numeric.
Why and what should I define to intercept for plotting the y axis or for
plotting axes in boxplot etc. Simply importing and overriding Axis as
function does not bring anything, it wouldn't get called.

Also I was not able to use S4 methods to redefine Axis. Overriding it
with the code from above using any of the following signatures also
didn't work for me - they are simply ignored:

setGeneric("Axis")

setMethod("Axis", signature(x="missing",at="numeric"), AxisFUN)
setMethod("Axis", signature(x="numeric",at="missing"), AxisFUN)

setMethod("Axis", signature(x="missing",at="ANY"), AxisFUN)
setMethod("Axis", signature(x="ANY",at="missing"), AxisFUN)
setMethod("Axis", signature(x="ANY",at="ANY"), AxisFUN)

Any ideas?

Thanks,
Oleg

Dr Oleg Sklyar
Technology Group
Man Investments Ltd
+44 (0)20 7144 3803
osklyar at maninvestments.com


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