Fix HDF5Matrix issue when working in conjunction with TimeSeriesGenerator (#10334)

* Fix issue when working in conjunction with TimeSeriesGenerator

The TimeSeriesGenerator class uses xrange through six which caused an IndexError

* Add test

* Add corresponding test

* Fix for python3

* Simplified code

* Fix indent

* Fix test

keras/utils/io_utils.py

@@ -83,13 +83,12 @@ class HDF5Matrix(object):
                 idx = (self.start + key).tolist()
             else:
                 raise IndexError
-        elif isinstance(key, list):
+        else:
+            # Assume list/iterable
             if max(key) + self.start < self.end:
                 idx = [x + self.start for x in key]
             else:
                 raise IndexError
-        else:
-            raise IndexError
         if self.normalizer is not None:
             return self.normalizer(self.data[idx])
         else:

tests/keras/utils/io_utils_test.py

@@ -90,8 +90,10 @@ def test_io_utils(in_tmpdir):
     with pytest.raises(IndexError):
         X_train[[1000, 1001]]
     with pytest.raises(IndexError):
-        X_train[np.array([1000])]
+        X_train[six.moves.range(1000, 1001)]
     with pytest.raises(IndexError):
+        X_train[np.array([1000])]
+    with pytest.raises(TypeError):
         X_train[None]
     assert (X_train[0] == X_train[:1][0]).all()
     assert (X_train[[0, 1]] == X_train[:2]).all()