BUG: Accept kwargs kind and na_position in Series.sort_index (GH13589)

Author: sahildua2305

doc/source/whatsnew/v0.19.0.txt

@@ -731,3 +731,5 @@ Bug Fixes
 - Bug where ``pd.read_gbq()`` could throw ``ImportError: No module named discovery`` as a result of a naming conflict with another python package called apiclient  (:issue:`13454`)
 - Bug in ``Index.union`` returns an incorrect result with a named empty index (:issue:`13432`)
 - Bugs in ``Index.difference`` and ``DataFrame.join`` raise in Python3 when using mixed-integer indexes (:issue:`13432`, :issue:`12814`)
+
+- Bug in ``Series.sort_index`` didn't accept kwargs ``kind`` and ``na_position`` (:issue:`13589`)

pandas/core/series.py

@@ -1756,7 +1756,7 @@ def _try_kind_sort(arr):
 
     @Appender(generic._shared_docs['sort_index'] % _shared_doc_kwargs)
     def sort_index(self, axis=0, level=None, ascending=True, inplace=False,
-                   sort_remaining=True):
+                   kind='quicksort', na_position='last', sort_remaining=True):
 
         axis = self._get_axis_number(axis)
         index = self.index
@@ -1765,12 +1765,15 @@ def sort_index(self, axis=0, level=None, ascending=True, inplace=False,
                                                  sort_remaining=sort_remaining)
         elif isinstance(index, MultiIndex):
             from pandas.core.groupby import _lexsort_indexer
-            indexer = _lexsort_indexer(index.labels, orders=ascending)
+            indexer = _lexsort_indexer(index.labels, orders=ascending,
+                                       na_position=na_position)
             indexer = _ensure_platform_int(indexer)
             new_index = index.take(indexer)
         else:
             new_index, indexer = index.sort_values(return_indexer=True,
-                                                   ascending=ascending)
+                                                   ascending=ascending,
+                                                   kind=kind,
+                                                   na_position=na_position)
 
         new_values = self._values.take(indexer)
         result = self._constructor(new_values, index=new_index)