ONNX export: broadcast_to, tile ops (apache#13981)

* Expand,tile op export

* fix

* adding test cases

* adding comments

python/mxnet/contrib/onnx/mx2onnx/_op_translations.py

@@ -1969,3 +1969,79 @@ def convert_roipooling(node, **kwargs):
         name=name
     )
     return [node]
+
+
+@mx_op.register("tile")
+def convert_tile(node, **kwargs):
+    """Map MXNet's Tile operator attributes to onnx's Tile
+    operator and return the created node.
+    """
+    name, input_nodes, attrs = get_inputs(node, kwargs)
+
+    reps_list = convert_string_to_list(attrs["reps"])
+
+    initializer = kwargs["initializer"]
+    reps_shape_np = np.array(reps_list, dtype='int64')
+    data_type = onnx.mapping.NP_TYPE_TO_TENSOR_TYPE[reps_shape_np.dtype]
+    dims = np.shape(reps_shape_np)
+
+    output_shape_name = "reps_attr_tensor" + str(kwargs["idx"])
+    tensor_node = onnx.helper.make_tensor_value_info(output_shape_name, data_type, dims)
+
+    initializer.append(
+        onnx.helper.make_tensor(
+            name=output_shape_name,
+            data_type=data_type,
+            dims=dims,
+            vals=reps_list,
+            raw=False,
+        )
+    )
+
+    input_nodes.append(output_shape_name)
+    tile_node = onnx.helper.make_node(
+        "Tile",
+        input_nodes,
+        [name],
+        name=name
+    )
+
+    return [tensor_node, tile_node]
+
+
+@mx_op.register("broadcast_to")
+def convert_broadcast_to(node, **kwargs):
+    """Map MXNet's broadcast_to operator attributes to onnx's Expand
+    operator and return the created node.
+    """
+    name, input_nodes, attrs = get_inputs(node, kwargs)
+
+    shape_list = convert_string_to_list(attrs["shape"])
+
+    initializer = kwargs["initializer"]
+    output_shape_np = np.array(shape_list, dtype='int64')
+    data_type = onnx.mapping.NP_TYPE_TO_TENSOR_TYPE[output_shape_np.dtype]
+    dims = np.shape(output_shape_np)
+
+    output_shape_name = "expand_attr_tensor" + str(kwargs["idx"])
+    tensor_node = onnx.helper.make_tensor_value_info(output_shape_name, data_type, dims)
+
+    initializer.append(
+        onnx.helper.make_tensor(
+            name=output_shape_name,
+            data_type=data_type,
+            dims=dims,
+            vals=shape_list,
+            raw=False,
+        )
+    )
+
+    input_nodes.append(output_shape_name)
+    expand_node = onnx.helper.make_node(
+        "Expand",
+        input_nodes,
+        [name],
+        name=name
+    )
+
+    return [tensor_node, expand_node]

tests/python-pytest/onnx/test_node.py

@@ -31,7 +31,7 @@
 from collections import namedtuple
 import numpy as np
 import numpy.testing as npt
-from onnx import numpy_helper, helper, load_model
+from onnx import checker, numpy_helper, helper, load_model
 from onnx import TensorProto
 from mxnet.test_utils import download
 from mxnet.contrib import onnx as onnx_mxnet
@@ -206,6 +206,18 @@ def test_imports(self):
                 mxnet_out = bkd_rep.run(inputs)
                 npt.assert_almost_equal(np_out, mxnet_out, decimal=4)
 
+    def test_exports(self):
+        input_shape = (2,1,3,1)
+        for test in export_test_cases:
+            test_name, onnx_name, mx_op, attrs = test
+            input_sym = mx.sym.var('data')
+            outsym = mx_op(input_sym, **attrs)
+            converted_model = onnx_mxnet.export_model(outsym, {}, [input_shape], np.float32,
+                                                      onnx_file_path=outsym.name + ".onnx")
+            model = load_model(converted_model)
+            checker.check_model(model)
+
+
 # test_case = ("test_case_name", mxnet op, "ONNX_op_name", [input_list], attribute map, MXNet_specific=True/False,
 # fix_attributes = {'modify': {mxnet_attr_name: onnx_attr_name},
 #                   'remove': [attr_name],
@@ -274,5 +286,11 @@ def test_imports(self):
     ("test_lpnormalization_ord2", "LpNormalization", [get_rnd([5, 3, 3, 2])], np.linalg.norm, {'ord':2, 'axis':1})
 ]
 
+# test_case = ("test_case_name", "ONNX_op_name", mxnet_op, attribute map)
+export_test_cases = [
+    ("test_expand", "Expand", mx.sym.broadcast_to, {'shape': (2,1,3,1)}),
+    ("test_tile", "Tile", mx.sym.tile, {'reps': (2,3)})
+]
+
 if __name__ == '__main__':
     unittest.main()