I am trying to build an R application in C++ using RInside. I wanted to save the plots as images in specified directory using codes,
png(filename = "filename", width = 600, height = 400)
xyplot(data ~ year | segment, data = dataset, layout = c(1,3),
type = c("l", "p"), ylab = "Y Label", xlab = "X Label",
main = "Title of the Plot")
dev.off()
It creates a png
file in the specified directory if directly run from R. But using C++ calls from RInside, I was not able to reproduce the same result. (I could reproduce all base plots using C++ calls. Problem with only Lattice and ggplots)
I used following codes as well,
myplot <- xyplot(data ~ year | segment, data = dataset, layout = c(1,3),
type = c("l", "p"), ylab = "Y Label", xlab = "X Label",
main = "Title of the Plot")
trellis.device(device = "png", filename = "filename")
print(myplot)
dev.off()
png
file is getting created if I run the above code in R without any problem. But from C++ calls, a png
file with empty panel with title and x-y label is getting created and not a complete plot.
I'm using the function R.parseEval()
for C++ call to R.
How to get proper lattice and ggplot2 plots properly?
The following prints a lattice xyplot
to a png. It is a minimal example, done as a variation
around rinside_sample11.cpp
.
#include <RInside.h> // for the embedded R via RInside
#include <unistd.h>
int main(int argc, char *argv[]) {
// create an embedded R instance
RInside R(argc, argv);
// evaluate an R expression with curve()
// because RInside defaults to interactive=false we use a file
std::string cmd = "library(lattice); "
"tmpf <- tempfile('xyplot', fileext='.png'); "
"png(tmpf); "
"print(xyplot(Girth ~ Height | equal.count(Volume), data=trees)); "
"dev.off();"
"tmpf";
// by running parseEval, we get the last assignment back, here the filename
std::string tmpfile = R.parseEval(cmd);
std::cout << "Can now use plot in " << tmpfile << std::endl;
exit(0);
}
It creates this file for me: