On 10 August 2013 at 14:17, Prof Brian Ripley wrote:
| On 09/08/2013 22:48, Boris Aronshtam wrote:
| > I need to create a data.frame from C-language and populate it. I Know how
to create lists from C, but I cannot figure out how to create a data.frame.
Does anyone have a sample code for creating a data.frame, setting column names,
and populating it with data?
|
| Use data.frame() via an eval() call from C.
|
| Or see the code is stats/src/model.c, as part of model.frame.default
| (but I would only do that if speed were essential).
Or if C++ is an option for you, below if a six-line Rcpp source example:
R> sourceCpp("/tmp/dataframe.cpp") ## see the file below
R> set.seed(42); getDataFrame(5) ## set RNG seed, request a dataframe
a b
1 1.370958 0.457742
2 -0.564698 0.719112
3 0.363128 0.934672
4 0.632863 0.255429
5 0.404268 0.462293
R>
The source file used above follows below.
Dirk
#include <Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export]]
DataFrame getDataFrame(int n) {
NumericVector a = rnorm(n);
NumericVector b = runif(n);
return DataFrame::create(Named("a") = a,
Named("b") = b);
}
--
Dirk Eddelbuettel | e...@debian.org | http://dirk.eddelbuettel.com
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