Adding error catches to the R interface

Currently the interface crashes the R session if any arguments are wrong or if it is called from the wrong directory. This is very disruptive. I have added some minimal error checks. It should probably have more for the other arguments.

Author: NathanSkene

R/svm.R

@@ -1,25 +1,29 @@
-if(Sys.info()['sysname'] == 'Windows'){
-	if(!file.exists("../build/bin/Debug/thundersvm.dll")){
-		print("Please build the library first!")
-		quit()
+check_location <- function(){
+	if(Sys.info()['sysname'] == 'Windows'){
+		if(!file.exists("../build/bin/Debug/thundersvm.dll")){
+			print("Please build the library first!")
+			quit()
+		}
+		dyn.load("../build/bin/Debug/thundersvm.dll")
+	} else if(Sys.info()['sysname'] == 'Linux'){
+		if(!file.exists("../build/lib/libthundersvm.so")){
+			print("Please build the library first!")
+			quit()
+		}
+		dyn.load("../build/lib/libthundersvm.so")
+	} else if(Sys.info()['sysname'] == 'Darwin'){
+		if(!file.exists("../build/lib/libthundersvm.dylib")){
+			print("Please build the library first!")
+			quit()
+		}
+		dyn.load("../build/lib/libthundersvm.dylib")
+	} else{
+	    print("OS not supported!")
+	    quit()
 	}
-	dyn.load("../build/bin/Debug/thundersvm.dll")
-} else if(Sys.info()['sysname'] == 'Linux'){
-	if(!file.exists("../build/lib/libthundersvm.so")){
-		print("Please build the library first!")
-		quit()
-	}
-	dyn.load("../build/lib/libthundersvm.so")
-} else if(Sys.info()['sysname'] == 'Darwin'){
-    	if(!file.exists("../build/lib/libthundersvm.dylib")){
-    		print("Please build the library first!")
-    		quit()
-    	}
-    	dyn.load("../build/lib/libthundersvm.dylib")
-} else{
-    print("OS not supported!")
-    quit()
 }
+check_location() # Run this when the file is sourced
+	
 svm_train_R <-
 function(
 svm_type = 0, kernel = 2,degree = 3,gamma = 'auto',
@@ -28,6 +32,8 @@ tol = 0.001, probability = FALSE, class_weight = 'None', cv = '-1',
 verbose = FALSE, max_iter = -1, n_cores = -1, dataset = 'None', model_file = 'None'
 )
 {
+	check_location()
+	if(!file.exists(dataset)){stop("The file containing the training dataset provided as an argument in 'dataset' does not exist")}
 	res <- .C("train_R", as.character(dataset), as.integer(kernel), as.integer(svm_type),
 	as.integer(degree), as.character(gamma), as.double(coef0), as.double(nu),
 	as.double(cost), as.double(epsilon), as.double(tol), as.integer(probability),
@@ -40,5 +46,8 @@ function(
 test_dataset = 'None', model_file = 'None', out_file = 'None'
 )
 {
+	check_location()
+	if(!file.exists(test_dataset)){stop("The file containing the training dataset provided as an argument in 'test_dataset' does not exist")}
+	if(!file.exists(model_file)){stop("The file containing the model provided as an argument in 'model_file' does not exist")}
 	res <- .C("predict_R", as.character(test_dataset), as.character(model_file), as.character(out_file))
-}
+}