fix doc to include description about __len__'
@@ -9,6 +9,8 @@ class TransformDataset(dataset_mixin.DatasetMixin):
dataset's :meth:`__getitem__`. Arrays returned by :meth:`__getitem__` of
the base dataset with integer as an argument are transformed by the given
function :obj:`transform`.
+ Also, :meth:`__len__` returns the integer returned by the base dataset's
+ :meth:`__len__`.
The function :obj:`transform` takes, as an argument, :obj:`in_data`, which
is the output of the base dataset's :meth:`__getitem__`, and returns
@@ -25,7 +27,9 @@ class TransformDataset(dataset_mixin.DatasetMixin):
Args:
dataset: The underlying dataset. The index of this dataset corresponds
- to the index of the base dataset.
+ to the index of the base dataset. This object needs to support
+ functions :meth:`__getitem__` and :meth:`__len__` as described
+ above.
transform (callable): A function that is called to transform values
returned by the underlying dataset's :meth:`__getitem__`.
