fix sparse

Author: jreback

pandas/core/internals.py

@@ -543,11 +543,21 @@ def convert(self, copy=True, **kwargs):
 
         return self.copy() if copy else self
 
-    def _can_hold_element(self, value):
-        raise NotImplementedError()
+    def _can_hold_element(self, element):
+        """ require the same dtype as ourselves """
+        dtype = self.values.dtype.type
+        if is_list_like(element):
+            element = np.asarray(element)
+            tipo = element.dtype.type
+            return issubclass(tipo, dtype)
+        return isinstance(element, dtype)
 
-    def _try_cast(self, value):
-        raise NotImplementedError()
+    def _try_cast(self, element):
+        dtype = self.values.dtype
+        try:
+            return dtype(element)
+        except:  # pragma: no cover
+            return element
 
     def _try_cast_result(self, result, dtype=None):
         """ try to cast the result to our original type, we may have