Expand short slices

If a slice is shorter than the shape provided to `reformat_slices`,
assume that the user wanted to include everything in those remaining
dimensions. So simply tack on an `Ellipsis` to the slices. This way it
automatically includes everything else after the given slice(s).

kenjutsu/format.py

@@ -222,8 +222,13 @@ def reformat_slices(slices, lengths=None):
         pass
 
     if new_lengths is not None and el_idx is None:
-        if len(new_slices) != len(new_lengths):
-            raise ValueError("Shape must be the same as the number of slices.")
+        if len(new_slices) < len(new_lengths):
+            new_slices += (Ellipsis,)
+            el_idx = new_slices.index(Ellipsis)
+        elif len(new_slices) > len(new_lengths):
+            raise ValueError(
+                "Shape must be as large or larger than the number of slices."
+            )
     elif new_lengths is not None:
         if (len(new_slices) - 1) > len(new_lengths):
             raise ValueError(

tests/test_format.py

@@ -270,11 +270,13 @@ def test_reformat_slice(self):
 
     def test_reformat_slices(self):
         with self.assertRaises(ValueError) as e:
-            format.reformat_slices((slice(None),), (1, 2))
+            format.reformat_slices(
+                (slice(None), slice(None)), (1,)
+            )
 
         self.assertEqual(
             str(e.exception),
-            "Shape must be the same as the number of slices."
+            "Shape must be as large or larger than the number of slices."
         )
 
         with self.assertRaises(ValueError) as e:
@@ -350,12 +352,24 @@ def test_reformat_slices(self):
             (slice(0, 10, 1),)
         )
 
+        rf_slice = format.reformat_slices(slice(None), (1, 2))
+        self.assertEqual(
+            rf_slice,
+            (slice(0, 1, 1), slice(0, 2, 1))
+        )
+
         rf_slice = format.reformat_slices((slice(None),), 10)
         self.assertEqual(
             rf_slice,
             (slice(0, 10, 1),)
         )
 
+        rf_slice = format.reformat_slices((slice(None),), (1, 2))
+        self.assertEqual(
+            rf_slice,
+            (slice(0, 1, 1), slice(0, 2, 1))
+        )
+
         rf_slice = format.reformat_slices((
             -1,
             slice(None),

tests/test_kenjutsu.py

@@ -195,14 +195,6 @@ def test_reformat_slice(self):
 
 
     def test_reformat_slices(self):
-        with self.assertRaises(ValueError) as e:
-            kenjutsu.reformat_slices((slice(None),), (1, 2))
-
-        self.assertEqual(
-            str(e.exception),
-            "Shape must be the same as the number of slices."
-        )
-
         with self.assertRaises(ValueError) as e:
             kenjutsu.reformat_slices(
                 (slice(None), slice(None), Ellipsis), (1,)