When is it an advantage/disadvantage to be using RDotNet for making statistical calculations as opposed to generating an R script text file and running it from the application using e.g. Process.Start? Or is there some other better way?
I need to execute a large number of commands and have a feeling that sending them one by one to R takes a lot of time.
I'd say the following two scenario's are stereotypical:
R.NET currently can initilize once. Parallel execution will be problematic.
Would suggest use RScript.
Our solution based on this answer on stackoverflow Call R (programming language) from .net
With monor change, we send R code from string and save it to temp file, since user run custom R code when needed.
public static void RunFromCmd(string batch, params string[] args)
{
// Not required. But our R scripts use allmost all CPU resources if run multiple instances
lock (typeof(REngineRunner))
{
string file = string.Empty;
string result = string.Empty;
try
{
// Save R code to temp file
file = TempFileHelper.CreateTmpFile();
using (var streamWriter = new StreamWriter(new FileStream(file, FileMode.Open, FileAccess.Write)))
{
streamWriter.Write(batch);
}
// Get path to R
var rCore = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\R-core") ??
Registry.CurrentUser.OpenSubKey(@"SOFTWARE\R-core");
var is64Bit = Environment.Is64BitProcess;
if (rCore != null)
{
var r = rCore.OpenSubKey(is64Bit ? "R64" : "R");
var installPath = (string)r.GetValue("InstallPath");
var binPath = Path.Combine(installPath, "bin");
binPath = Path.Combine(binPath, is64Bit ? "x64" : "i386");
binPath = Path.Combine(binPath, "Rscript");
string strCmdLine = @"/c """ + binPath + @""" " + file;
if (args.Any())
{
strCmdLine += " " + string.Join(" ", args);
}
var info = new ProcessStartInfo("cmd", strCmdLine);
info.RedirectStandardInput = false;
info.RedirectStandardOutput = true;
info.UseShellExecute = false;
info.CreateNoWindow = true;
using (var proc = new Process())
{
proc.StartInfo = info;
proc.Start();
result = proc.StandardOutput.ReadToEnd();
}
}
else
{
result += "R-Core not found in registry";
}
Console.WriteLine(result);
}
catch (Exception ex)
{
throw new Exception("R failed to compute. Output: " + result, ex);
}
finally
{
if (!string.IsNullOrWhiteSpace(file))
{
TempFileHelper.DeleteTmpFile(file, false);
}
}
}
}
Full blog post: http://kostylizm.blogspot.ru/2014/05/run-r-code-from-c-sharp.html
With Process.Start you will start up a new R session. This can take some time, especially if you are using different packages in your script which you need to load.
If you use R.NET, you can create an R instance, and keep on talking with it. So if you have created a webservice to connect R with ASP you don't want to start up R all the time as this will be very time costly. You need it just once and you can work with it interactively.
