BUG: fix integer-slicing from integers-as-floats, GH #670

Author: wesm

pandas/core/indexing.py

@@ -220,7 +220,7 @@ def _convert_to_indexer(self, obj, axis=0):
         is_int_index = _is_integer_index(labels)
         if isinstance(obj, slice):
 
-            int_slice = _is_integer_slice(obj)
+            int_slice = _is_index_slice(obj)
             null_slice = obj.start is None and obj.stop is None
             # could have integers in the first level of the MultiIndex
             position_slice = (int_slice
@@ -234,7 +234,7 @@ def _convert_to_indexer(self, obj, axis=0):
                     i, j = labels.slice_locs(obj.start, obj.stop)
                     slicer = slice(i, j, obj.step)
                 except Exception:
-                    if _is_integer_slice(obj):
+                    if _is_index_slice(obj):
                         if labels.inferred_type == 'integer':
                             raise
                         slicer = obj
@@ -276,7 +276,7 @@ def _get_slice_axis(self, slice_obj, axis=0):
         axis_name = obj._get_axis_name(axis)
         labels = getattr(obj, axis_name)
 
-        int_slice = _is_integer_slice(slice_obj)
+        int_slice = _is_index_slice(slice_obj)
 
         null_slice = slice_obj.start is None and slice_obj.stop is None
         # could have integers in the first level of the MultiIndex
@@ -289,7 +289,7 @@ def _get_slice_axis(self, slice_obj, axis=0):
                 i, j = labels.slice_locs(slice_obj.start, slice_obj.stop)
                 slicer = slice(i, j, slice_obj.step)
             except Exception:
-                if _is_integer_slice(slice_obj):
+                if _is_index_slice(slice_obj):
                     if labels.inferred_type == 'integer':
                         raise
                     slicer = slice_obj
@@ -301,9 +301,12 @@ def _get_slice_axis(self, slice_obj, axis=0):
 
         return self._slice(slicer, axis=axis)
 
-def _is_integer_slice(obj):
+def _is_index_slice(obj):
+    def _is_valid_index(x):
+        return com.is_integer(x) or com.is_float(x) and np.allclose(x, int(x))
+
     def _crit(v):
-        return v is None or com.is_integer(v)
+        return v is None or _is_valid_index(v)
 
     both_none = obj.start is None and obj.stop is None
 

pandas/tests/test_series.py

@@ -483,6 +483,17 @@ def test_slice_can_reorder_not_uniquely_indexed(self):
         s = Series(1, index=['a', 'a', 'b', 'b', 'c'])
         result = s[::-1] # it works!
 
+    def test_slice_float_get_set(self):
+        result = self.ts[4.0:10.0]
+        expected = self.ts[4:10]
+        assert_series_equal(result, expected)
+
+        self.ts[4.0:10.0] = 0
+        self.assert_((self.ts[4:10] == 0).all())
+
+        self.assertRaises(TypeError, self.ts.__getitem__, slice(4.5, 10.0))
+        self.assertRaises(TypeError, self.ts.__setitem__, slice(4.5, 10.0), 0)
+
     def test_setitem(self):
         self.ts[self.ts.index[5]] = np.NaN
         self.ts[[1,2,17]] = np.NaN