c# - Using R in asp.net web application -

i trying use r script in asp.net c# web application. trying use simple r script concatenate 2 strings single one.

below cs code

using rdotnet;  using system; using system.collections.generic; using system.io; using system.linq; using system.web; using system.web.ui; using system.web.ui.webcontrols;  public partial class _default : system.web.ui.page {     protected void page_load(object sender, eventargs e)     {     }      private static double evaluateexpression(rengine engine, string expression)     {         var expressionvector = engine.createcharactervector(new[] { expression });         engine.setsymbol("expr", expressionvector);          //  wrong -- need parse expression before evaluation         //var result = engine.evaluate("eval(expr)");          //  right way this!!!         var result = engine.evaluate("eval(parse(text=expr))");         var ret = result.asnumeric().first();          return ret;     }      public static void setuppath(string rversion = "r-3.2.1")     {         var oldpath = system.environment.getenvironmentvariable("path");         var rpath = system.environment.is64bitprocess ?                                string.format(@"c:\program files\r\{0}\bin\x64", rversion) :                                string.format(@"c:\program files\r\{0}\bin\i386", rversion);          if (!directory.exists(rpath))             throw new directorynotfoundexception(               string.format(" r.dll not found in : {0}", rpath));         var newpath = string.format("{0}{1}{2}", rpath,                                      system.io.path.pathseparator, oldpath);         system.environment.setenvironmentvariable("path", newpath);     }      protected void button1_click(object sender, eventargs e)     {         setuppath();         rengine.setenvironmentvariables();          rengine engine = rengine.getinstance();         // rengine requires explicit initialization.         // can set parameters.         engine.initialize();         //engine.evaluate("g<-5+3+2");         engine.evaluate("g<-paste('hello r', 'test')");         label1.text = evaluateexpression(engine, "g").tostring();     } } 

i have click button , when click want output showed in web page.

when run code , click button getting text

nan

in label control page. when run

engine.evaluate("g<-5+3+2");  

instead of

engine.evaluate("g<-paste('hello r', 'test')"); 

i getting correct value 10 in label of page. not aware of error , dont know how output in web page. tried in websites code has been written console applications , nothing asp.net web application.

can me problem solved displaying r output in web page?

you don't need evaluateexpression @ all. use engine.getsymbol("g") instead.

the nan output happens because of asnumeric() conversion inside evaluateexpression. work numeric output, not character.

here's minimal example numeric , character variables:

    static void main(string[] args)     {         rengine.setenvironmentvariables();         rengine engine = rengine.getinstance();         engine.initialize();         engine.evaluate("x <- 40 + 2");         engine.evaluate("s <- paste('hello', letters[5])");         var x = engine.getsymbol("x").asnumeric().first();         var s = engine.getsymbol("s").ascharacter().first();         console.writeline(x);         console.writeline(s);     }