index_what_you_can

Author: toobaz

pandas/core/indexes/multi.py

@@ -1035,11 +1035,13 @@ def is_lexsorted(self):
         """
         return self.lexsort_depth == self.nlevels
 
-    def is_lexsorted_for_tuple(self, tup):
+    def _true_slices_indices(self, tup):
         """
-        Return True if we are correctly lexsorted given the passed tuple
+        Return indices of (non-trivial) slices in "tup"
         """
-        return len(tup) <= self.lexsort_depth
+        slices = lambda k : (isinstance(k, slice)
+                             and (k.start is not None or k.stop is not None))
+        return [(i if slices(k) else -1) for (i, k) in enumerate(tup)]
 
     @cache_readonly
     def lexsort_depth(self):
@@ -2262,12 +2264,12 @@ def get_locs(self, tup):
         """
 
         # must be lexsorted to at least as many levels
-        if not self.is_lexsorted_for_tuple(tup):
+        last_slice = max(self._true_slices_indices(tup))
+        if last_slice > self.lexsort_depth:
             raise UnsortedIndexError('MultiIndex Slicing requires the index '
-                                     'to be fully lexsorted tuple len ({0}), '
+                                     'to be lexsorted: slicing on level ({0}), '
                                      'lexsort depth ({1})'
-                                     .format(len(tup), self.lexsort_depth))
-
+                                     .format(last_slice, self.lexsort_depth))
         # indexer
         # this is the list of all values that we want to select
         n = len(self)