Hello all,
Recently i've been forced to output results from a Wavelet transform to
files because storing of objects in R took too much memory.
The exported objects are lighter than the objects produced by the
Wavelet package in R so i can re-import them in R.
Problem is..i have 400 object of 16,5 Mb each. and it take about 6 hours
to reimport in R! I use the readr package as this is the fastest base
function in R.
I thus explore the benefits of using directly C++ with Rcpp to see if it
can lead me to significant gains.
The idea is to read the file and store it into an Rcpp matrix being
returned in R.
I adapted a C++ code to use Rcpp, it compiles but when using it it
crashes R:
#include <Rcpp.h>
#include <fstream>
#include <sstream>
#include <string>
using namespace Rcpp;
// [[Rcpp::export]]
NumericMatrix readfilecpp()
{
NumericMatrix output;
std::ifstream myfile("/home/ogami/outBvTem_17dwt_1.csv");
for (int row=0; row<15; ++row)
{
std::string line;
std::getline(myfile,line);
//if(!myfile.good())
//break;
std::stringstream iss(line);
for (int col=0; col<4600; ++col )
{
std::string val;
std::getline(iss,val,',');
//if (!iss.good())
//break;
std::stringstream convertor(val);
convertor >> output(row,col);
}
}
return(output);
}
any idea?
Thank you!
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