I've done it this way before:
eX -> ecdf(distribution 1)
eY -> ecdf(distribution 2)
par(mar=c(5,5,2,1),xlog=TRUE)
plot(eX, do.points=FALSE, verticals=TRUE, col="black", xlab=xlabel,
xlim=c(1,100000), ylab=ylabel,
lty=1, cex.lab=1.5, cex.axis=1.5, main="",
lwd=3,log="x")
plot(eY, do.points=FALSE, verticals=TRUE, col="blue", add=TRUE,
xlim=c(1,100000), main="")
Warning: It makes a stair-step that may be difficult to see unless you use
color. I had to change how the ecdf was plotted when I made b/w figures for
my publication so that different dashed lines were distinct.
HTH,
-Steve
-----Original Message-----
From: David Winsemius [mailto:dwinsem...@comcast.net]
Sent: Wednesday, May 02, 2012 10:17 AM
To: Johannes Radinger
Cc: R-help@r-project.org
Subject: Re: [R] Two ecdf with log-scales
On May 2, 2012, at 6:14 AM, Johannes Radinger wrote:
> Hi,
>
> i want to plot empirical cumulative density functions for two
> variables in one plot. For better visualizing the differences in the
> two cumulative curves I'd like to log-scale the axis.
>
> So far I found 3 possible functions to plot ecdf:
>
> 1) ecdf() from the package 'stats'. I don't know how to successfully
> set the log.scales? Combining two plots is not a problem:
>
> plot(ecdf(x1))
> lines(ecdf(x2),col.h="red")
>
> 2) gx.ecdf() from package 'rgr'. It is easily possible to plot log-
> scales, but I don't know how to plot two densities?
>
> gx.ecdf(x1,log=TRUE,ifqs = TRUE)
>
> 3) Ecdf() from package 'Hmisc'. No log-option directly available and
> here I also don't know how to 'stack' two plots...
>
> Ecdf(x1,what="F")
>
>
> Probably there are many more solutions (e.g. ggplot etc.)...
> ...Has anyone faced a similar task and found a simple solution? Any
> suggestions are welcome!
Have you searched the Archives? I seem to remember that the log(0) was a
barrier to persons attempting this in the past. (ISTR a posting in the last
few weeks.) Maybe you could also provide a test data object that has the
same range as your x1 and x 2 variables.
> and provide commented, minimal, self-contained, reproducible code.
--
David Winsemius, MD
West Hartford, CT
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