fix onnx conv2d_transpose loading (#245)

nnvm/python/nnvm/frontend/onnx.py

@@ -64,7 +64,8 @@ def _elemwise(name):
         assert len(inputs) == 2, "Math op take 2 inputs, {} given".format(len(inputs))
         op_name = _math_name_picker(name)(attr)
         axis = int(attr.get('axis', 0))
-        if op_name == 'broadcast_add' and inputs[0].attr('op_name') == 'conv2d':
+        conv_ops = ["conv2d", "conv2d_transpose"]
+        if op_name == 'broadcast_add' and inputs[0].attr('op_name') in conv_ops:
             # TODO(zhreshold): remove hard coded infershape
             inputs[1] = _sym.expand_dims(inputs[1], axis=axis, num_newaxis=2)
         return get_nnvm_op(op_name)(*inputs)
@@ -101,8 +102,10 @@ def _conv():
 def _conv_transpose():
     def _impl(inputs, attr, params):
         # get number of channels
-        channels = _infer_channels(inputs[1], params)
+        channels = _infer_channels(inputs[1], params, True)
         attr['channels'] = channels
+        groups = attr.pop('group')
+        attr['groups'] = groups
         return AttrCvt(
             op_name=_dimension_picker('conv', '_transpose'),
             transforms={