[MINOR] minor fixes in smote

replace the rbind/cbind with indexing
rand call is updated with a seed value

scripts/builtin/smote.dml

@@ -46,41 +46,54 @@ return (Matrix[Double] Y) {
     print("the number of samples should be an integral multiple of 100. Setting s = 100")
     s = 100
   }
+
+  if(k < 1) {
+    print("k should not be less than 1. Setting k value to default k = 1.")
+    k = 1
+  }
+
   # matrix to keep the index of KNN for each minority sample
-  knn_index = matrix(0,k,0)
+  knn_index = matrix(0,k,nrow(X))
   # find nearest neighbour
   for(i in 1:nrow(X))
   {
     knn = nn(X, X[i, ], k)
-    knn_index = cbind(knn_index, knn)
+    knn_index[, i] = knn
   }
 
   # number of synthetic samples from each minority class sample
-  iter = (s/100)
+  iter = 0
+  iterLim = (s/100)
   # matrix to store synthetic samples
-  synthetic_samples = matrix(0, 0, ncol(X))
-  while(iter > 0)
+  synthetic_samples = matrix(0, iterLim*ncol(knn_index), ncol(X))
+
+  # shuffle the nn indexes
+  if(k < iterLim)
+    rand_index = sample(k, iterLim, TRUE)
+  else 
+    rand_index = sample(k, iterLim)
+
+  while(iter < iterLim)
   {
-    # generate a random number
-    # TODO avoid duplicate random numbers
-    rand_index = as.integer(as.scalar(Rand(rows=1, cols=1, min=1, max=k)))
     # pick the random NN
-    knn_sample = knn_index[rand_index,] 
+    knn_sample = knn_index[as.scalar(rand_index[iter+1]),] 
     # generate sample    
     for(i in 1:ncol(knn_index))
     {
       index = as.scalar(knn_sample[1,i])
       X_diff = X[index,] - X[i, ]
-      gap = as.scalar(Rand(rows=1, cols=1, min=0, max=1))
+      gap = as.scalar(Rand(rows=1, cols=1, min=0, max=1, seed = 41))
       X_sys = X[i, ] + (gap*X_diff)
-      synthetic_samples = rbind(synthetic_samples, X_sys)
+      synthetic_samples[iter*ncol(knn_index)+i,] = X_sys;
     }
-    iter = iter - 1
+    iter = iter + 1
   }
 
   Y = synthetic_samples
+
   if(verbose)
     print(nrow(Y)+ " synthesized samples generated.")
+
 }
 
 

src/test/java/org/apache/sysds/test/functions/builtin/BuiltinSmoteTest.java

@@ -47,9 +47,14 @@ public void setUp() {
 		addTestConfiguration(TEST_NAME, new TestConfiguration(TEST_CLASS_DIR, TEST_NAME, new String[] {"C"}));
 	}
 
+	@Test
+	public void testSmote0CP() {
+		runSmoteTest(100, 1, LopProperties.ExecType.CP);
+	}
+
 	@Test
 	public void testSmote1CP() {
-		runSmoteTest(300, 3, LopProperties.ExecType.CP);
+		runSmoteTest(300, 10, LopProperties.ExecType.CP);
 	}
 
 	@Test