Implementing suggestions

Author: Neeratyoy

openml/datasets/dataset.py

@@ -368,17 +368,19 @@ def decode_arff(fh):
     def _convert_array_format(data, array_format, attribute_names):
         """Convert a dataset to a given array format.
 
+        Converts a non-sparse matrix to numpy array.
+        Converts a sparse matrix to a sparse dataframe.
+
         Parameters
         ----------
-        array_format : str
-            Tag to attach to the dataset to get a pandas SparseDataFrame or a
-            NumPy array instead.
+        array_format : str {'array', 'dataframe'}
+            Desired data type of the output
             - If array_format='array'
                 Converts non-sparse numeric data to numpy-array
                 Enforces numeric encoding of categorical columns
-                Missing values are represented as NaN in the dataframe
+                Missing values are represented as NaN in the numpy-array
             - If array_format='dataframe'
-                Convers sparse data to sparse dataframe
+                Converts sparse data to sparse dataframe
 
         """
         if array_format == "array" and not scipy.sparse.issparse(data):