R devel - Mar 2014 - C API to get numrow of data frame

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

	[[alternative HTML version deleted]]

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 at 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
>
>         [[alternative HTML version deleted]]
>
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