REF: nargsort incorrectly calling _values_for_argsort (pandas-dev#37266)

Author: jbrockmendel

doc/source/whatsnew/v0.24.1.rst

@@ -1,7 +1,7 @@
 .. _whatsnew_0241:
 
 What's new in 0.24.1 (February 3, 2019)
---------------------------------------
+---------------------------------------
 
 .. warning::
 

doc/source/whatsnew/v0.24.2.rst

@@ -1,7 +1,7 @@
 .. _whatsnew_0242:
 
 What's new in 0.24.2 (March 12, 2019)
-------------------------------------
+-------------------------------------
 
 .. warning::
 

pandas/core/arrays/base.py

@@ -507,7 +507,12 @@ def _values_for_argsort(self) -> np.ndarray:
         return np.array(self)
 
     def argsort(
-        self, ascending: bool = True, kind: str = "quicksort", *args, **kwargs
+        self,
+        ascending: bool = True,
+        kind: str = "quicksort",
+        na_position: str = "last",
+        *args,
+        **kwargs,
     ) -> np.ndarray:
         """
         Return the indices that would sort this array.
@@ -538,7 +543,14 @@ def argsort(
         # 2. argsort : total control over sorting.
         ascending = nv.validate_argsort_with_ascending(ascending, args, kwargs)
 
-        result = nargsort(self, kind=kind, ascending=ascending, na_position="last")
+        values = self._values_for_argsort()
+        result = nargsort(
+            values,
+            kind=kind,
+            ascending=ascending,
+            na_position=na_position,
+            mask=np.asarray(self.isna()),
+        )
         return result
 
     def argmin(self):

pandas/core/sorting.py

@@ -327,6 +327,7 @@ def nargsort(
     ascending: bool = True,
     na_position: str = "last",
     key: Optional[Callable] = None,
+    mask: Optional[np.ndarray] = None,
 ):
     """
     Intended to be a drop-in replacement for np.argsort which handles NaNs.
@@ -341,19 +342,27 @@ def nargsort(
     ascending : bool, default True
     na_position : {'first', 'last'}, default 'last'
     key : Optional[Callable], default None
+    mask : Optional[np.ndarray], default None
+        Passed when called by ExtensionArray.argsort.
     """
 
     if key is not None:
         items = ensure_key_mapped(items, key)
         return nargsort(
-            items, kind=kind, ascending=ascending, na_position=na_position, key=None
+            items,
+            kind=kind,
+            ascending=ascending,
+            na_position=na_position,
+            key=None,
+            mask=mask,
         )
 
     items = extract_array(items)
-    mask = np.asarray(isna(items))
+    if mask is None:
+        mask = np.asarray(isna(items))
 
     if is_extension_array_dtype(items):
-        items = items._values_for_argsort()
+        return items.argsort(ascending=ascending, kind=kind, na_position=na_position)
     else:
         items = np.asanyarray(items)