I think it is actually better to check the length of the row names. In case
the data frame has zero columns. (FIXME, of course.)

Gabor


On Mon, Mar 31, 2014 at 8:04 PM, Murray Stokely <murray@stokely.org> wrote:

> The simplest case would be:
>
>    int num_rows = Rf_length(VECTOR_ELT(dataframe, 0));
>    int num_columns = Rf_length(dataframe);
>
> There may be edge cases for which this doesn't work; would need to
> look into how the dim primitive is implemented to be sure.
>
>                - Murray
>
>
> On Mon, Mar 31, 2014 at 4:40 PM, Sandip Nandi <sannandi@umail.iu.edu>
> wrote:
> > Hi ,
> >
> > Is there any C API to the R API  nrow of dataframe ?
> >
> > x<- data.frame()
> > n<- nrow(x)
> > print(n)
> > 0
> >
> >
> > Example :
> > My C function which deals with data frame looks like and I don't to send
> > the  number of rows of data frame .I want to detect it from the function
> > itself, my function take data frame as argument and do some on it. I want
> > API equivalent to nrow. I tried Rf_nrows,Rf_ncols . No much help.
> >
> > SEXP  writeRR(SEXP dataframe) {
> >
> > }
> >
> >
> > Any help is very appreciated.
> >
> > Thanks,
> > Sandip
> >
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> >
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>
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