Fix sample_multinomial number of outputs bug

src/operator/random/sample_multinomial_op.h

@@ -68,7 +68,7 @@ inline bool SampleMultinomialOpShape(const nnvm::NodeAttrs& attrs,
   CHECK_EQ(in_attrs->size(), 1U);
   CHECK_EQ(out_attrs->size(), param.get_prob ? 2U : 1U);
   const mxnet::TShape& ishape = (*in_attrs)[0];
-  if (!shape_is_known(ishape)) return false;
+  if (!ndim_is_known(ishape)) return false;
 
   MSHADOW_TYPE_SWITCH(param.dtype, DType, {
     CHECK_LE(ishape[ishape.ndim() - 1], mxnet::common::MaxIntegerValue<DType>())
@@ -95,7 +95,10 @@ inline bool SampleMultinomialOpShape(const nnvm::NodeAttrs& attrs,
   }
   SHAPE_ASSIGN_CHECK(*out_attrs, 0, oshape);
   if (param.get_prob) SHAPE_ASSIGN_CHECK(*out_attrs, 1, oshape);
-  return shape_is_known(out_attrs->at(0)) && shape_is_known(out_attrs->at(1));
+  for (const auto& out_shape : *out_attrs){
+    if (!shape_is_known(out_shape)) return false;
+  }
+  return true;
 }
 
 

tests/python/unittest/test_random.py

@@ -916,6 +916,18 @@ def test_randint_without_dtype():
     a = mx.nd.random.randint(low=50000000, high=50000010, ctx=mx.context.current_context())
     assert a.dtype == np.int32
 
+
+@with_seed()
+def test_sample_multinomial_num_outputs():
+    ctx = mx.context.current_context()
+    probs = [[0.125, 0.25, 0.25], [0.0625, 0.125, 0.1875]]
+    out = mx.nd.random.multinomial(data=mx.nd.array(probs, ctx=ctx), shape=10000, get_prob=False)
+    assert isinstance(out, mx.nd.NDArray)
+    out = mx.nd.random.multinomial(data=mx.nd.array(probs, ctx=ctx), shape=10000, get_prob=True)
+    assert isinstance(out, list)
+    assert len(out) == 2
+
+
 if __name__ == '__main__':
     import nose
     nose.runmodule()