Fix a bug that was caused when dataset was partialed.

skorch/net.py

@@ -805,7 +805,7 @@ def get_dataset(self, X, y=None):
 
         """
         dataset = self.dataset
-        is_initialized = not isinstance(dataset, type)
+        is_initialized = not callable(dataset)
 
         kwargs = self._get_params_for('dataset')
         if kwargs and is_initialized:
@@ -819,8 +819,7 @@ def get_dataset(self, X, y=None):
         if 'use_cuda' not in kwargs:
             kwargs['use_cuda'] = self.use_cuda
 
-        dataset = self.dataset(X, y, **kwargs)
-        return dataset
+        return dataset(X, y, **kwargs)
 
     def get_iterator(self, dataset, train=False):
         """Get an iterator that allows to loop over the batches of the

skorch/tests/test_net.py

@@ -1,5 +1,6 @@
 """Tests for net.py"""
 
+from functools import partial
 import pickle
 from unittest.mock import Mock
 from unittest.mock import patch
@@ -688,6 +689,15 @@ def test_net_initialized_with_initalized_dataset(
         )
         net.fit(*data)  # does not raise
 
+    def test_net_initialized_with_partialed_dataset(
+            self, net_cls, module_cls, data, dataset_cls):
+        net = net_cls(
+            module_cls,
+            dataset=partial(dataset_cls, use_cuda=0),
+            max_epochs=1,
+        )
+        net.fit(*data)  # does not raise
+
     def test_net_initialized_with_initalized_dataset_and_kwargs_raises(
             self, net_cls, module_cls, data, dataset_cls):
         net = net_cls(