Fix #569: crash when sklearn version does not collide (#601)

* reinstantiate flow

* reinstantiate flow fix

* pep8 problems

* pep8 fix

Author: janvanrijn

openml/flows/flow.py

@@ -310,19 +310,6 @@ def _from_dict(cls, xml_dict):
         arguments['model'] = None
         flow = cls(**arguments)
 
-        # try to parse to a model because not everything that can be
-        # deserialized has to come from scikit-learn. If it can't be
-        # serialized, but comes from scikit-learn this is worth an exception
-        if (
-            arguments['external_version'].startswith('sklearn==')
-            or ',sklearn==' in arguments['external_version']
-        ):
-            from .sklearn_converter import flow_to_sklearn
-            model = flow_to_sklearn(flow)
-        else:
-            model = None
-        flow.model = model
-
         return flow
 
     def publish(self):

openml/flows/functions.py

@@ -8,20 +8,36 @@
 import openml.utils
 
 
-def get_flow(flow_id):
+def get_flow(flow_id, reinstantiate=False):
     """Download the OpenML flow for a given flow ID.
 
     Parameters
     ----------
     flow_id : int
         The OpenML flow id.
+
+    reinstantiate: bool
+        Whether to reinstantiate the flow to a sklearn model.
+        Note that this can only be done with sklearn flows, and
+        when
+
+    Returns
+    -------
+    flow : OpenMLFlow
+        the flow
     """
     flow_id = int(flow_id)
     flow_xml = openml._api_calls._perform_api_call("flow/%d" % flow_id)
 
     flow_dict = xmltodict.parse(flow_xml)
     flow = OpenMLFlow._from_dict(flow_dict)
 
+    if reinstantiate:
+        if not (flow.external_version.startswith('sklearn==') or
+                ',sklearn==' in flow.external_version):
+            raise ValueError('Only sklearn flows can be reinstantiated')
+        flow.model = openml.flows.flow_to_sklearn(flow)
+
     return flow
 
 

tests/test_flows/test_flow.py

@@ -275,9 +275,9 @@ def test_existing_flow_exists(self):
         for classifier in [nb, complicated]:
             flow = openml.flows.sklearn_to_flow(classifier)
             flow, _ = self._add_sentinel_to_flow_name(flow, None)
-            #publish the flow
+            # publish the flow
             flow = flow.publish()
-            #redownload the flow
+            # redownload the flow
             flow = openml.flows.get_flow(flow.flow_id)
 
             # check if flow exists can find it
@@ -329,7 +329,8 @@ def test_sklearn_to_upload_to_flow(self):
         # Check whether we can load the flow again
         # Remove the sentinel from the name again so that we can reinstantiate
         # the object again
-        new_flow = openml.flows.get_flow(flow_id=flow.flow_id)
+        new_flow = openml.flows.get_flow(flow_id=flow.flow_id,
+                                         reinstantiate=True)
 
         local_xml = flow._to_xml()
         server_xml = new_flow._to_xml()

tests/test_runs/test_run_functions.py

@@ -627,7 +627,8 @@ def test_get_run_trace(self):
             flow_exists = openml.flows.flow_exists(flow.name, flow.external_version)
             self.assertIsInstance(flow_exists, int)
             self.assertGreater(flow_exists, 0)
-            downloaded_flow = openml.flows.get_flow(flow_exists)
+            downloaded_flow = openml.flows.get_flow(flow_exists,
+                                                    reinstantiate=True)
             setup_exists = openml.setups.setup_exists(downloaded_flow)
             self.assertIsInstance(setup_exists, int)
             self.assertGreater(setup_exists, 0)