Small ND4J/SameDiff fixes (#248)

* #8218 Fix Nd4j.hstack rank 1 case

Signed-off-by: AlexDBlack <blacka101@gmail.com>

* #8209 SameDiff: don't allow empty arrays (with 0s in shape) for variables

Signed-off-by: AlexDBlack <blacka101@gmail.com>

nd4j/nd4j-backends/nd4j-api-parent/nd4j-api/src/main/java/org/nd4j/autodiff/samediff/SameDiff.java

@@ -3367,7 +3367,9 @@ public class SameDiff extends SDBaseOps {
      */
     public SDVariable var(@NonNull String name, @NonNull VariableType variableType, WeightInitScheme weightInitScheme,
                           org.nd4j.linalg.api.buffer.DataType dataType, long... shape) {
-
+        for(long l : shape){
+            Preconditions.checkArgument(l != 0, "Cannot create variable with a shape that contains zeros (empty array shape) - got shape %s", shape);
+        }
 
         if (name == null || name.length() < 1)
             name = getNewVarName();
@@ -3582,7 +3584,7 @@ public class SameDiff extends SDBaseOps {
         Preconditions.checkState(arr.dataType().isFPType(), "Cannot create variable with non-floating point type:" +
                 " provided array has datatype %s. Variables must be floating point type to be trainable by backpropagation.\n" +
                 "For non floating point types, these should be created as placeholders or constants instead.", arr.dataType());
-
+        Preconditions.checkArgument(!arr.isEmpty(), "Empty arrays cannot be used when creating variables. Array shape: %ndShape", arr);
 
         if (name == null || name.length() < 1)
             name = getNewVarName();

nd4j/nd4j-backends/nd4j-api-parent/nd4j-api/src/main/java/org/nd4j/linalg/factory/BaseNDArrayFactory.java

@@ -17,6 +17,7 @@
 package org.nd4j.linalg.factory;
 
 
+import lombok.NonNull;
 import lombok.val;
 import org.nd4j.base.Preconditions;
 import org.nd4j.linalg.api.blas.*;
@@ -959,8 +960,18 @@ public abstract class BaseNDArrayFactory implements NDArrayFactory {
      *
      * @param arrs
      */
-    public INDArray hstack(INDArray... arrs) {
+    public INDArray hstack(@NonNull INDArray... arrs) {
-        return Nd4j.concat(1, arrs);
+        int firstRank = arrs[0].rank();
+        Preconditions.checkState(firstRank > 0 && firstRank <= 2, "Only rank 1 and 2 arrays may be horizontally stacked; first input has rank %ndRank shape %nhShape", arrs[0], arrs[0]);
+        for( int i=1; i<arrs.length; i++ ){
+            Preconditions.checkState(firstRank == arrs[i].rank(), "Array ranks must be equal for horizontal stacking, arrs[0].rank=%s, arrs[%s].rank=%s",
+                    arrs[0].rank(), i, arrs[i].rank());
+        }
+        if(firstRank == 1){
+            return Nd4j.concat(0, arrs);
+        } else {
+            return Nd4j.concat(1, arrs);
+        }
     }
 
     /**
@@ -972,7 +983,6 @@ public abstract class BaseNDArrayFactory implements NDArrayFactory {
     @Override
     public INDArray vstack(final INDArray... arrs) {
         return Nd4j.concat(0, arrs);
-
     }
 
 

nd4j/nd4j-backends/nd4j-tests/src/test/java/org/nd4j/autodiff/samediff/SameDiffTests.java

@@ -3563,4 +3563,26 @@ public class SameDiffTests extends BaseNd4jTest {
         assertEquals(casted.dataType(), DataType.FLOAT);
         assertTrue(casted.getShapeDescriptor().isEmpty());
     }
+
+
+    @Test
+    public void testEmptyShapeVar(){
+        SameDiff sd = SameDiff.create();
+
+        try {
+            sd.var(DataType.FLOAT, 1, 0, 2);
+            fail("Expected exception");
+        } catch (IllegalArgumentException e){
+            String m = e.getMessage();
+            assertTrue(m, m.contains("variable") && m.contains("empty") && m.contains("0"));
+        }
+
+        try {
+            sd.var(Nd4j.create(1, 0, 2));
+            fail("Expected exception");
+        } catch (IllegalArgumentException e){
+            String m = e.getMessage().toLowerCase();
+            assertTrue(m, m.contains("variable") && m.contains("empty") && m.contains("0"));
+        }
+    }
 }

nd4j/nd4j-backends/nd4j-tests/src/test/java/org/nd4j/linalg/Nd4jTestsC.java

@@ -8122,6 +8122,19 @@ public class Nd4jTestsC extends BaseNd4jTest {
         return ret;
     }
 
+
+    @Test
+    public void testVStackHStack1d() {
+        INDArray rowVector1 = Nd4j.create(new double[]{1,2,3});
+        INDArray rowVector2 = Nd4j.create(new double[]{4,5,6});
+
+        INDArray vStack = Nd4j.vstack(rowVector1, rowVector2);      //Vertical stack:   [3]+[3] to [2,3]
+        INDArray hStack = Nd4j.hstack(rowVector1, rowVector2);      //Horizontal stack: [3]+[3] to [6]
+
+        assertEquals(Nd4j.createFromArray(1.0,2,3,4,5,6).reshape('c', 2, 3), vStack);
+        assertEquals(Nd4j.createFromArray(1.0,2,3,4,5,6), hStack);
+    }
+
     @Override
     public char ordering() {
         return 'c';