# R-alpha: ECDFs

**Peter Dalgaard BSA
**
p.dalgaard@kubism.ku.dk

*22 Aug 1997 00:48:30 +0200*

Kurt Hornik <hornik@ci.tuwien.ac.at> writes:
>*
*>* >>>>> Thomas Lumley writes:
*>*
*>* > On Tue, 19 Aug 1997, Kurt Hornik wrote:
*>* >>
*>* >> Here's something what is needed for teaching elementary statistics:
*>* >> Given a sample vector x, compute the corresponding ECDF, plot it, and
*>* >> perhaps evaluate it at points other than the data points.
*>*
*>* > The approx() function is supposed to do this (it currently only does
*>* > linear interpolation). If the right and left continuous step
*>* > functions were added to approx then we could easily use approxfun to
*>* > define the ECDF as a function closure, making it automatically
*>* > available at any point you want. After all, the ECDF *is* a function.
*>*
*>* Ah, very nice idea!
*>*
*>* So, we'd have
*>*
*>* ecdf(x)
*>*
*>* return a FUNCTION of class (e.g.) "step" which would on the one hand
*>* have the right methods for it and on the other hand would allow us to
*>* evaluate it at new points right away?
*>*
*>* Martin, Peter?
*>*
*
Neat idea. And - hey! - someone has made it possible to assign classes
to a function now. I looked into that a while ago with a view to kill
off the antipedagogical habit that R and S has of dumping screenfulls
of gibberish on the unsuspecting newbie. At that time, it wasn't
possible so I dropped it, meaning to take it up on the list later on.
That would be like
print.function<-function(f)cat("Use 'show' to see content of function\n")
show<-unclass
Hmm. Do we want something like this? It clashes a little with other
uses of function classes, but not badly as far as I can see.
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk) FAX: (+45) 35327907
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