Adding __str__ for OpenMLDataset

Author: Neeratyoy

openml/datasets/dataset.py

@@ -173,6 +173,28 @@ def __init__(self, name, description, format=None,
         else:
             self.data_pickle_file = None
 
+    def __str__(self):
+        object_dict = self.__dict__
+        output_str = ''
+        name = '\n%14s: %s\n' % ("Name", object_dict['name'])
+        version = '%14s: %s\n' % ("Version", object_dict['version'])
+        format = '%14s: %s\n' % ("Format", object_dict['format'])
+        date = '%14s: %s\n' % ("Upload Date", object_dict['upload_date'].replace('T', ' '))
+        licence = '%14s: %s\n' % ("Licence", object_dict['licence'])
+        d_url = '%14s: %s\n' % ("Download URL", object_dict['url'])
+        base_url = 'https://www.openml.org/d/'
+        w_url = '%14s: %s\n' % ("OpenML URL", base_url + str(self.dataset_id))
+        local_file = '%14s: %s\n' % ("Data file", object_dict['data_file'])
+        pickle_file = '%14s: %s\n' % ("Pickle file", object_dict['data_pickle_file'])
+        num_instances = ''
+        if object_dict['qualities']['NumberOfInstances'] is not None:
+            num_instances = '%14s: %d\n' % ("# of instances",
+                                            object_dict['qualities']['NumberOfInstances'])
+        num_features = '%14s: %d\n' % ("# of features", len(object_dict['features']))
+        output_str = name + version + format + date + licence + d_url + w_url + local_file + \
+            pickle_file + num_instances + num_features
+        return(output_str)
+
     def _data_arff_to_pickle(self, data_file):
         data_pickle_file = data_file.replace('.arff', '.pkl.py3')
         if os.path.exists(data_pickle_file):