[Rcpp-devel] Rcpp can not return big DataFrame

[Romain Francois]

Hmm. This does fix the problem:

   DataFrame PLrecord = DataFrame::create(
         Named("txn.qty"  , wrap( txn_qty  ) ),
         Named("txn.prc"  , wrap( txn_prc  ) ),
         Named("txn.fee"  , wrap( txn_fee  ) ),
         Named("pos.qty"  , wrap( pos_qty  ) ),
         Named("close.prc", wrap( close_prc) ),
         Named("PL"       , wrap( PL       ) )
   );

So we might do something wrong with copying objects.

Le 27/03/13 14:19, 该走了 a écrit :
> Dear Rcpp developer,
>    I am tried return a big DataFrame from Rcpp to R, but met some problem!
>
> ### begin dataframetest.cpp
>
> #include <Rcpp.h>
> using namespace Rcpp;
> using namespace std;
>
> // [[Rcpp::export]]
> DataFrame dataframetest(NumericVector close){
>    int nrow = close.size();
>    vector<double>  txn_qty = vector<double>(nrow);
>    vector<double> txn_prc = vector<double>(nrow);
>    vector<double>  txn_fee = vector<double>(nrow);
>    vector<double>  pos_qty = vector<double>(nrow);
>    vector<double>  close_prc = as<vector<double> >(close);
>    vector<double>  PL = vector<double>(nrow);
>    DataFrame PLrecord = DataFrame::create(Named("txn.qty", txn_qty),
> Named("txn.prc", txn_prc),
> Named("txn.fee", txn_fee),
> Named("pos.qty", pos_qty),
> Named("close.prc", close_prc),
> Named("PL", PL));
>    return PLrecord;
> }
> #### end  dataframetest.cpp
>
> ### R code
> n <- 4e5
> x.prc <- 1:n
> library(Rcpp)
> sourceCpp("./dataframetest.cpp")
> aa <- dataframetest(x.prc)
>
> ##### end R code
>
>   When n is big, like 4e5, then it will exhaust the memory or crash;
> when n is small, like  4e3, it can return the correct DataFrame. I was
> wondering if Rcpp::DataFrame can handle so big DataFrame. In my opinion,
> n = 4e5 is not big, I can create such a long data.frame from R code
> easily, without any problem. Why Rcpp can not? Or I miss something?
>
> ### R code
> n <- 4e5
> x.prc <- rnorm(n)
> a <- data.frame(x = x.prc,
>         y = x.prc,
>                  d = x.prc,
>                  e = x.prc,
>                  f = x.prc,
>                  k = x.prc)
> head(a)
>              x           y           d           e           f           k
> 1 -0.45145433 -0.45145433 -0.45145433 -0.45145433 -0.45145433 -0.45145433
> 2 -0.55851370 -0.55851370 -0.55851370 -0.55851370 -0.55851370 -0.55851370
> 3  0.18209145  0.18209145  0.18209145  0.18209145  0.18209145  0.18209145
> 4 -0.56092768 -0.56092768 -0.56092768 -0.56092768 -0.56092768 -0.56092768
> 5  0.25689622  0.25689622  0.25689622  0.25689622  0.25689622  0.25689622
> 6 -0.04558792 -0.04558792 -0.04558792 -0.04558792 -0.04558792 -0.04558792
>
> #### sessionInfo
> sessionInfo()
> R version 2.15.3 (2013-03-01)
> Platform: x86_64-suse-linux-gnu (64-bit)
>
> locale:
>   [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
>   [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
>   [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
>   [7] LC_PAPER=C                 LC_NAME=C
>   [9] LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
> [1] Rcpp_0.10.3      data.table_1.8.8
>
> loaded via a namespace (and not attached):
> [1] compiler_2.15.3 tools_2.15.3
>
>
>
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> Rcpp-devel at lists.r-forge.r-project.org
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>


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Romain Francois
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