fix version comparison (#200)

nnvm/python/nnvm/frontend/mxnet.py

@@ -13,14 +13,6 @@ def _get_nnvm_op(op_name):
         raise RuntimeError("Unable to map op_name {} to nnvm.sym".format(op_name))
     return op
 
-def _get_mxnet_version():
-    try:
-        import mxnet as mx
-        version = mx.__version__
-    except ImportError:
-        version = '0.11.1'
-    return [int(x) for x in version.split('.')]
-
 def _required_attr(attr, key):
     assert isinstance(attr, dict)
     if key not in attr:
@@ -127,14 +119,19 @@ def _conv2d_transpose(inputs, attrs):
     return _get_nnvm_op(op_name)(*inputs, **new_attrs)
 
 def _dense(inputs, attrs):
+    import mxnet as mx
     op_name, new_attrs = 'dense', {}
     new_attrs['units'] = _required_attr(attrs, 'num_hidden')
     new_attrs['use_bias'] = not _parse_bool_str(attrs, 'no_bias')
-    major, minor, micro = _get_mxnet_version()
-    if major >= 0 and minor >= 11 and micro >= 1:
-        use_flatten = _parse_bool_str(attrs, 'flatten', 'True')
-        if use_flatten:
-            inputs[0] = _sym.flatten(inputs[0])
+    try:
+        _ = mx.sym.FullyConnected(mx.sym.var('x'), num_hidden=1, flatten=True)
+        has_flatten = True
+    except mx.base.MXNetError:
+        # no flatten attribute in old mxnet
+        has_flatten = False
+    use_flatten = _parse_bool_str(attrs, 'flatten', 'True')
+    if has_flatten and use_flatten:
+        inputs[0] = _sym.flatten(inputs[0])
     return _get_nnvm_op(op_name)(*inputs, **new_attrs)
 
 def _dropout(inputs, attrs):