Add support for keras upsampling (#305)

* Add support for keras upsampling

* Fix code formatting

* Fix indentation

* Fix indentation round 2

* Hide unused parameter

* Only enable UpSampling2D since the others are not currently supported by TVM

* Improve error messages and code layout

nnvm/python/nnvm/frontend/keras.py

@@ -268,6 +268,31 @@ def _convert_pooling(insym, keras_layer, symtab):
             raise TypeError("Unsupported pooling type : {}".format(keras_layer))
 
 
+def _convert_upsample(insym, keras_layer, _):
+    _check_data_format(keras_layer)
+    upsample_type = type(keras_layer).__name__
+
+    if upsample_type == "UpSampling1D":
+        h = keras_layer.size
+        params = {'scale': h}
+    elif upsample_type == "UpSampling2D":
+        h, w = keras_layer.size
+        if h != w:
+            raise TypeError("Unsupported upsampling type with different axes size : {}"
+                            .format(keras_layer.size))
+        params = {'scale': h}
+    elif upsample_type == "UpSampling3D":
+        h, w, d = keras_layer.size
+        if h != w or w != d:
+            raise TypeError("Unsupported upsampling type with different axes size : {}"
+                            .format(keras_layer.size))
+        params = {'scale': h}
+    else:
+        raise TypeError("Unsupported upsampling type : {}".format(upsample_type))
+
+    return _sym.upsampling(insym, **params)
+
+
 def _convert_batchnorm(insym, keras_layer, symtab):
     params = {'scale': False,
               'center': False,
@@ -358,6 +383,7 @@ _convert_map = {
     'Subtract'                 : _convert_merge,
     'Multiply'                 : _convert_merge,
     'ZeroPadding2D'            : _convert_padding,
+    'UpSampling2D'           : _convert_upsample,
 
     # 'ZeroPadding1D'          : _convert_padding,
     # 'AveragePooling1D'       : _convert_pooling,
@@ -367,7 +393,7 @@ _convert_map = {
     # 'Cropping1D'             : _convert_cropping,
     # 'Cropping2D'             : _convert_cropping,
     # 'UpSampling1D'           : _convert_upsample,
-    # 'UpSampling2D'           : _convert_upsample,
+    # 'UpSampling3D'           : _convert_upsample,
     # 'Conv1D'                 : _convert_convolution1d,
 
     # 'GRU'                    : _convert_gru,