store predictions_url in runs (#783)

* store predictions_url in runs

* can't test when uploading a new run as we don't have details locally

* Fix PEP8

Author: amueller

openml/runs/functions.py

@@ -687,10 +687,13 @@ def obtain_field(xml_obj, fieldname, from_server, cast=None):
                              '(OpenML server error?)')
     else:
         output_data = run['oml:output_data']
+        predictions_url = None
         if 'oml:file' in output_data:
             # multiple files, the normal case
             for file_dict in output_data['oml:file']:
                 files[file_dict['oml:name']] = int(file_dict['oml:file_id'])
+                if file_dict['oml:name'] == 'predictions':
+                    predictions_url = file_dict['oml:url']
         if 'oml:evaluation' in output_data:
             # in normal cases there should be evaluations, but in case there
             # was an error these could be absent
@@ -757,8 +760,8 @@ def obtain_field(xml_obj, fieldname, from_server, cast=None):
                      dataset_id=dataset_id, output_files=files,
                      evaluations=evaluations,
                      fold_evaluations=fold_evaluations,
-                     sample_evaluations=sample_evaluations,
-                     tags=tags)
+                     sample_evaluations=sample_evaluations, tags=tags,
+                     predictions_url=predictions_url)
 
 
 def _get_cached_run(run_id):

tests/test_runs/test_run_functions.py

@@ -1112,6 +1112,12 @@ def test_get_run(self):
             self.assertEqual(run.fold_evaluations['f_measure'][0][i], value)
         assert ('weka' in run.tags)
         assert ('weka_3.7.12' in run.tags)
+        assert (
+            run.predictions_url == (
+                "https://www.openml.org/data/download/1667125/"
+                "weka_generated_predictions4575715871712251329.arff"
+            )
+        )
 
     def _check_run(self, run):
         self.assertIsInstance(run, dict)