[R] Plotting two ecdf curves on same axes

[Frank E Harrell Jr]

On Tue, 15 Oct 2002 17:30:17 +0200 (MEST)
Jane McFerren <jane.mcferren at lycos.co.uk> wrote:

> Dear R listers
> 
> Could somebody please advise me how to draw two empirical cumulative distribution 
> functions on the same set of axes?
> 
> I know I should be using the ecdf command but I'm not sure what to add to it to force it 
> to plot twice on the axes
> 
> Thanks
> Jane
> ______________________________________________________

One way is

library(Hmisc)
ecdf(~ y, groups=grouping.variable)

You can also produce multiple panels:

ecdf(~ y | state, groups=urban.vs.rural)

-- 
Frank E Harrell Jr              Prof. of Biostatistics & Statistics
Div. of Biostatistics & Epidem. Dept. of Health Evaluation Sciences
U. Virginia School of Medicine  http://hesweb1.med.virginia.edu/biostat
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