Possible performance improvement

Author: yred

pandas/core/format.py

@@ -617,7 +617,7 @@ def get_col_type(dtype):
                 lev3 = [blank] * clevels
                 for level_idx, group in itertools.groupby(
                         self.frame.index.labels[i]):
-                    count = len(list(group))
+                    count = sum(1 for _ in group)
                     lev3.extend([lev2[level_idx]] + [blank] * (count - 1))
                 strcols.insert(i, lev3)