[R] Add function to histogram?
Jim Lemon
bitwrit at ozemail.com.au
Wed Sep 21 21:27:36 CEST 2005
Robert Lundqvist wrote:
> Is there any neat way to add a curve (frequency function or the like) to a
> histogram or other plots? I haven't found one yet...
>
For a general solution, one usually has to scale the density function to
fit the plot. The simple, but convenient, function rescale() in the
plotrix package can be used like this:
add.density.curve<-function(y,density=NA) {
xyrange<-par("usr")
if(is.na(density)) y.density<-density(y)
lines(seq(xyrange[1],xyrange[2],length=length(y.density$y)),
rescale(y.density$y,c(0,xyrange[4])))
}
This only works for histograms, but I am working on a general function
that will outsmart the habit of some functions of running the plot range
into negative numbers when these are not possible (i.e. you can't have a
negative count in a histogram - or a negative density except in the very
latest physics).
Jim
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