[R] Re: Error in model.frame

Ross Boylan ross at biostat.ucsf.edu
Sat Aug 16 01:15:41 CEST 2003

On Fri, 2003-08-15 at 16:03, Ross Boylan wrote:
> I am getting an error that I don't understand, and wonder if anyone
> could explain what's going on.  I call a function defined thus:
> clogit.rds<-function(formula,data,extra.data,response.prob,
>                  na.action=getOption("na.action"),subset=NULL,
>                  control=coxph.control()){
>     method="exact"  # only option for now
>     mf<-match.call()
>     mf[[1]]<-as.name("model.frame")
>     mf$method<-mf$control<-NULL
>     mfn<-mf
>     mfn$na.action<-"I"
>     mfn$subset<-NULL
>     nrows<-NROW(eval(mfn,parent.frame()))
> etc.
> At the eval on the last line, I get
> Error in model.frame(formula, rownames, variables, varnames, extras,
> extranames,  : 
> 	variable lengths differ
A clue: if I call this with response.prob set to an element of the
clogit.rds argument data frame, I don't get the error.

I assume that to fix this I must somehow exclude this variable.  But I
will need it back in when I make the next call.  Suggestions?  Insights
into why this is necessary?

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