From c0006689286b8d2cc224be6aed4583bb4dee9a19 Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Tue, 17 Nov 2020 23:30:56 +0000
Subject: [PATCH 01/21] fix idxmax/min for Series with underlying 'Int'
 datatype

---
 pandas/core/arrays/base.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index bd5cf43e19e9f..7a4faadf07986 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -591,7 +591,7 @@ def argsort(
             mask=np.asarray(self.isna()),
         )
 
-    def argmin(self):
+    def argmin(self, *args):
         """
         Return the index of minimum value.
 
@@ -608,7 +608,7 @@ def argmin(self):
         """
         return nargminmax(self, "argmin")
 
-    def argmax(self):
+    def argmax(self, *args):
         """
         Return the index of maximum value.
 

From 163208105fe1abe2c579879878ea349bfa82de26 Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Wed, 18 Nov 2020 02:01:31 +0000
Subject: [PATCH 02/21] test added

---
 pandas/tests/series/test_reductions.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pandas/tests/series/test_reductions.py b/pandas/tests/series/test_reductions.py
index c3c58f29fcbf6..2736e774aee52 100644
--- a/pandas/tests/series/test_reductions.py
+++ b/pandas/tests/series/test_reductions.py
@@ -114,3 +114,7 @@ def test_validate_stat_keepdims():
     )
     with pytest.raises(ValueError, match=msg):
         np.sum(ser, keepdims=True)
+
+def test_idxmax_with_nullable_integer_dtype():
+    s = Series([1, 2, 3], dtype="Int64")
+    s.idxmax()
\ No newline at end of file

From 8018586e15688e44f82e0daf0f5d46a357a533e5 Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Wed, 18 Nov 2020 02:18:41 +0000
Subject: [PATCH 03/21] editted test

---
 pandas/tests/series/test_reductions.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/pandas/tests/series/test_reductions.py b/pandas/tests/series/test_reductions.py
index 2736e774aee52..c301deb908d19 100644
--- a/pandas/tests/series/test_reductions.py
+++ b/pandas/tests/series/test_reductions.py
@@ -115,6 +115,8 @@ def test_validate_stat_keepdims():
     with pytest.raises(ValueError, match=msg):
         np.sum(ser, keepdims=True)
 
-def test_idxmax_with_nullable_integer_dtype():
-    s = Series([1, 2, 3], dtype="Int64")
-    s.idxmax()
\ No newline at end of file
+
+def test_idxmax_idxmin_with_nullable_integer_dtype():
+    ser = Series([1, 2, 3], dtype="Int64")
+    assert ser.idxmax() == 2
+    assert ser.idxmin() == 0

From b076d23849b2b150a748d50c8dcfc0f2f2ddf4cf Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Thu, 19 Nov 2020 12:15:44 +0000
Subject: [PATCH 04/21] added test for argmax argmin

---
 pandas/tests/series/test_reductions.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pandas/tests/series/test_reductions.py b/pandas/tests/series/test_reductions.py
index c301deb908d19..961f8fe7138b2 100644
--- a/pandas/tests/series/test_reductions.py
+++ b/pandas/tests/series/test_reductions.py
@@ -120,3 +120,9 @@ def test_idxmax_idxmin_with_nullable_integer_dtype():
     ser = Series([1, 2, 3], dtype="Int64")
     assert ser.idxmax() == 2
     assert ser.idxmin() == 0
+
+
+def test_argmax_argmin_with_nullable_integer_dtype():
+    ser = Series([1, 2, 3], dtype="Int64")
+    assert ser.argmax() == 2
+    assert ser.argmin() == 0

From 664e4ecd0a05e3c86a65da2541c2a8f4b0cb00e4 Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Fri, 20 Nov 2020 00:23:28 +0000
Subject: [PATCH 05/21] added validations

---
 pandas/core/arrays/base.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 7a4faadf07986..51526df89bced 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -591,7 +591,7 @@ def argsort(
             mask=np.asarray(self.isna()),
         )
 
-    def argmin(self, *args):
+    def argmin(self, axis=None, *args, **kwargs):
         """
         Return the index of minimum value.
 
@@ -606,9 +606,10 @@ def argmin(self, *args):
         --------
         ExtensionArray.argmax
         """
+        nv.validate_argmin(axis, args, kwargs)
         return nargminmax(self, "argmin")
 
-    def argmax(self, *args):
+    def argmax(self, axis=None, *args, **kwargs):
         """
         Return the index of maximum value.
 
@@ -623,6 +624,7 @@ def argmax(self, *args):
         --------
         ExtensionArray.argmin
         """
+        nv.validate_argmax(axis, args, kwargs)
         return nargminmax(self, "argmax")
 
     def fillna(self, value=None, method=None, limit=None):

From 8403c38d09f8007f97941f891c9440c5a9d1d649 Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Fri, 20 Nov 2020 11:35:43 +0000
Subject: [PATCH 06/21] The overhaul

---
 pandas/core/arrays/base.py             |  6 ++---
 pandas/core/base.py                    | 28 +++++++++++++++++-----
 pandas/core/series.py                  | 32 +++++++++++++++++++-------
 pandas/tests/series/test_reductions.py |  8 +++++++
 4 files changed, 56 insertions(+), 18 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 51526df89bced..bd5cf43e19e9f 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -591,7 +591,7 @@ def argsort(
             mask=np.asarray(self.isna()),
         )
 
-    def argmin(self, axis=None, *args, **kwargs):
+    def argmin(self):
         """
         Return the index of minimum value.
 
@@ -606,10 +606,9 @@ def argmin(self, axis=None, *args, **kwargs):
         --------
         ExtensionArray.argmax
         """
-        nv.validate_argmin(axis, args, kwargs)
         return nargminmax(self, "argmin")
 
-    def argmax(self, axis=None, *args, **kwargs):
+    def argmax(self):
         """
         Return the index of maximum value.
 
@@ -624,7 +623,6 @@ def argmax(self, axis=None, *args, **kwargs):
         --------
         ExtensionArray.argmin
         """
-        nv.validate_argmax(axis, args, kwargs)
         return nargminmax(self, "argmax")
 
     def fillna(self, value=None, method=None, limit=None):
diff --git a/pandas/core/base.py b/pandas/core/base.py
index 54dec90c08aa2..8d06c7f8a7ac2 100644
--- a/pandas/core/base.py
+++ b/pandas/core/base.py
@@ -715,9 +715,17 @@ def argmax(self, axis=None, skipna: bool = True, *args, **kwargs) -> int:
         the minimum cereal calories is the first element,
         since series is zero-indexed.
         """
-        nv.validate_minmax_axis(axis)
-        nv.validate_argmax_with_skipna(skipna, args, kwargs)
-        return nanops.nanargmax(self._values, skipna=skipna)
+        delegate = self._values
+
+        if isinstance(delegate, ExtensionArray):
+            # dispatch to ExtensionArray interface
+            return delegate.argmax()
+
+        else:
+            # dispatch to numpy arrays
+            nv.validate_minmax_axis(axis)
+            skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
+            return nanops.nanargmax(delegate, skipna=skipna)
 
     def min(self, axis=None, skipna: bool = True, *args, **kwargs):
         """
@@ -765,9 +773,17 @@ def min(self, axis=None, skipna: bool = True, *args, **kwargs):
 
     @doc(argmax, op="min", oppose="max", value="smallest")
     def argmin(self, axis=None, skipna=True, *args, **kwargs) -> int:
-        nv.validate_minmax_axis(axis)
-        nv.validate_argmax_with_skipna(skipna, args, kwargs)
-        return nanops.nanargmin(self._values, skipna=skipna)
+        delegate = self._values
+
+        if isinstance(delegate, ExtensionArray):
+            # dispatch to ExtensionArray interface
+            return delegate.argmin()
+
+        else:
+            # dispatch to numpy arrays
+            nv.validate_minmax_axis(axis)
+            skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
+            return nanops.nanargmin(delegate, skipna=skipna)
 
     def tolist(self):
         """
diff --git a/pandas/core/series.py b/pandas/core/series.py
index d4ae5c2245b5b..b0a60b4a9de1c 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2076,10 +2076,18 @@ def idxmin(self, axis=0, skipna=True, *args, **kwargs):
         >>> s.idxmin(skipna=False)
         nan
         """
-        skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
-        i = nanops.nanargmin(self._values, skipna=skipna)
-        if i == -1:
-            return np.nan
+        delegate = self._values
+
+        if isinstance(delegate, ExtensionArray):
+            # dispatch to ExtensionArray interface
+            i = delegate.argmin()
+
+        else:
+            # dispatch to numpy arrays
+            skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
+            i = nanops.nanargmin(delegate, skipna=skipna)
+            if i == -1:
+                return np.nan
         return self.index[i]
 
     def idxmax(self, axis=0, skipna=True, *args, **kwargs):
@@ -2147,10 +2155,18 @@ def idxmax(self, axis=0, skipna=True, *args, **kwargs):
         >>> s.idxmax(skipna=False)
         nan
         """
-        skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
-        i = nanops.nanargmax(self._values, skipna=skipna)
-        if i == -1:
-            return np.nan
+        delegate = self._values
+
+        if isinstance(delegate, ExtensionArray):
+            # dispatch to ExtensionArray interface
+            i = delegate.argmax()
+
+        else:
+            # dispatch to numpy arrays
+            skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
+            i = nanops.nanargmax(delegate, skipna=skipna)
+            if i == -1:
+                return np.nan
         return self.index[i]
 
     def round(self, decimals=0, *args, **kwargs) -> "Series":
diff --git a/pandas/tests/series/test_reductions.py b/pandas/tests/series/test_reductions.py
index 961f8fe7138b2..b9aa0acc50db3 100644
--- a/pandas/tests/series/test_reductions.py
+++ b/pandas/tests/series/test_reductions.py
@@ -126,3 +126,11 @@ def test_argmax_argmin_with_nullable_integer_dtype():
     ser = Series([1, 2, 3], dtype="Int64")
     assert ser.argmax() == 2
     assert ser.argmin() == 0
+
+
+def test_with_nullable_float_dtype():
+    ser = Series([1, 2, 3], dtype="Float64")
+    assert ser.idxmax() == 2
+    assert ser.idxmin() == 0
+    assert ser.argmax() == 2
+    assert ser.argmin() == 0

From 741c97adcc630ce087f8058b9df4970da2f49917 Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Tue, 24 Nov 2020 20:19:46 +0000
Subject: [PATCH 07/21] 2nd attempt

---
 pandas/core/base.py   | 24 ++++++++++++------------
 pandas/core/series.py | 17 ++++++++++-------
 2 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/pandas/core/base.py b/pandas/core/base.py
index 8d06c7f8a7ac2..8b1ee8a04b822 100644
--- a/pandas/core/base.py
+++ b/pandas/core/base.py
@@ -716,15 +716,15 @@ def argmax(self, axis=None, skipna: bool = True, *args, **kwargs) -> int:
         since series is zero-indexed.
         """
         delegate = self._values
+        nv.validate_minmax_axis(axis)
+        skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
 
         if isinstance(delegate, ExtensionArray):
-            # dispatch to ExtensionArray interface
-            return delegate.argmax()
-
+            if not skipna and isna(delegate).any():
+                return -1
+            else:
+                return delegate.argmax()
         else:
-            # dispatch to numpy arrays
-            nv.validate_minmax_axis(axis)
-            skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
             return nanops.nanargmax(delegate, skipna=skipna)
 
     def min(self, axis=None, skipna: bool = True, *args, **kwargs):
@@ -774,15 +774,15 @@ def min(self, axis=None, skipna: bool = True, *args, **kwargs):
     @doc(argmax, op="min", oppose="max", value="smallest")
     def argmin(self, axis=None, skipna=True, *args, **kwargs) -> int:
         delegate = self._values
+        nv.validate_minmax_axis(axis)
+        skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
 
         if isinstance(delegate, ExtensionArray):
-            # dispatch to ExtensionArray interface
-            return delegate.argmin()
-
+            if not skipna and isna(delegate).any():
+                return -1
+            else:
+                return delegate.argmin()
         else:
-            # dispatch to numpy arrays
-            nv.validate_minmax_axis(axis)
-            skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
             return nanops.nanargmin(delegate, skipna=skipna)
 
     def tolist(self):
diff --git a/pandas/core/series.py b/pandas/core/series.py
index b0a60b4a9de1c..7384ef73e6f58 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2077,13 +2077,15 @@ def idxmin(self, axis=0, skipna=True, *args, **kwargs):
         nan
         """
         delegate = self._values
+        skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
 
         if isinstance(delegate, ExtensionArray):
-            # dispatch to ExtensionArray interface
-            i = delegate.argmin()
+            if not skipna and isna(delegate).any():
+                return np.nan
+            else:
+                i = delegate.argmin()
 
         else:
-            # dispatch to numpy arrays
             skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
             i = nanops.nanargmin(delegate, skipna=skipna)
             if i == -1:
@@ -2156,14 +2158,15 @@ def idxmax(self, axis=0, skipna=True, *args, **kwargs):
         nan
         """
         delegate = self._values
+        skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
 
         if isinstance(delegate, ExtensionArray):
-            # dispatch to ExtensionArray interface
-            i = delegate.argmax()
+            if not skipna and isna(delegate).any():
+                return np.nan
+            else:
+                i = delegate.argmax()
 
         else:
-            # dispatch to numpy arrays
-            skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
             i = nanops.nanargmax(delegate, skipna=skipna)
             if i == -1:
                 return np.nan

From 131ae836801fcf0f1097db449bc910d71ed919af Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Tue, 24 Nov 2020 20:24:49 +0000
Subject: [PATCH 08/21] 2nd attempt

---
 pandas/core/series.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index 7384ef73e6f58..bb215c7a3f4c3 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2086,7 +2086,6 @@ def idxmin(self, axis=0, skipna=True, *args, **kwargs):
                 i = delegate.argmin()
 
         else:
-            skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
             i = nanops.nanargmin(delegate, skipna=skipna)
             if i == -1:
                 return np.nan

From 3269fb5dc519ead5acb91755119a3f520835ed2b Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Wed, 25 Nov 2020 23:48:49 +0000
Subject: [PATCH 09/21] simplified idxmaxmin and added parameterised tests

---
 pandas/core/series.py                  | 32 +++----------
 pandas/tests/series/test_reductions.py | 65 +++++++++++++++++++-------
 2 files changed, 53 insertions(+), 44 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index bb215c7a3f4c3..00a246b7ce34e 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2076,19 +2076,9 @@ def idxmin(self, axis=0, skipna=True, *args, **kwargs):
         >>> s.idxmin(skipna=False)
         nan
         """
-        delegate = self._values
-        skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
-
-        if isinstance(delegate, ExtensionArray):
-            if not skipna and isna(delegate).any():
-                return np.nan
-            else:
-                i = delegate.argmin()
-
-        else:
-            i = nanops.nanargmin(delegate, skipna=skipna)
-            if i == -1:
-                return np.nan
+        i = self.argmin(axis=None, skipna=skipna, *args, **kwargs)
+        if i == -1:
+            return np.nan
         return self.index[i]
 
     def idxmax(self, axis=0, skipna=True, *args, **kwargs):
@@ -2156,19 +2146,9 @@ def idxmax(self, axis=0, skipna=True, *args, **kwargs):
         >>> s.idxmax(skipna=False)
         nan
         """
-        delegate = self._values
-        skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
-
-        if isinstance(delegate, ExtensionArray):
-            if not skipna and isna(delegate).any():
-                return np.nan
-            else:
-                i = delegate.argmax()
-
-        else:
-            i = nanops.nanargmax(delegate, skipna=skipna)
-            if i == -1:
-                return np.nan
+        i = self.argmax(axis=None, skipna=skipna, *args, **kwargs)
+        if i == -1:
+            return np.nan
         return self.index[i]
 
     def round(self, decimals=0, *args, **kwargs) -> "Series":
diff --git a/pandas/tests/series/test_reductions.py b/pandas/tests/series/test_reductions.py
index b9aa0acc50db3..b9ef947373a71 100644
--- a/pandas/tests/series/test_reductions.py
+++ b/pandas/tests/series/test_reductions.py
@@ -1,5 +1,6 @@
 import numpy as np
 import pytest
+from datetime import datetime
 
 import pandas as pd
 from pandas import MultiIndex, Series
@@ -116,21 +117,49 @@ def test_validate_stat_keepdims():
         np.sum(ser, keepdims=True)
 
 
-def test_idxmax_idxmin_with_nullable_integer_dtype():
-    ser = Series([1, 2, 3], dtype="Int64")
-    assert ser.idxmax() == 2
-    assert ser.idxmin() == 0
-
-
-def test_argmax_argmin_with_nullable_integer_dtype():
-    ser = Series([1, 2, 3], dtype="Int64")
-    assert ser.argmax() == 2
-    assert ser.argmin() == 0
-
-
-def test_with_nullable_float_dtype():
-    ser = Series([1, 2, 3], dtype="Float64")
-    assert ser.idxmax() == 2
-    assert ser.idxmin() == 0
-    assert ser.argmax() == 2
-    assert ser.argmin() == 0
+@pytest.mark.parametrize('dtype', ['Int64', 'Float64'])
+@pytest.mark.parametrize(
+    "op_name, skipna, expected",
+    [
+        ('idxmax', True, 'b'),
+        ('idxmin', True, 'a'),
+        ('argmax', True, 1),
+        ('argmin', True, 0),
+        ('idxmax', False, np.nan),
+        ('idxmin', False, np.nan),
+        ('argmax', False, -1),
+        ('argmin', False, -1)
+    ]
+)
+def test_argminmax_idxminmax(dtype, op_name, skipna, expected):
+    ser = Series([1, 2, None], index=['a', 'b', 'c'], dtype=dtype)
+    result = getattr(ser, op_name)(skipna=skipna)
+    if pd.isna(expected):
+        assert np.isnan(result)
+    else:
+        assert result == expected
+
+
+@pytest.mark.parametrize(
+    "op_name, skipna, expected",
+    [
+        ('idxmax', True, 'b'),
+        ('idxmin', True, 'a'),
+        ('argmax', True, 1),
+        ('argmin', True, 0),
+        ('idxmax', False, np.nan),
+        ('idxmin', False, np.nan),
+        ('argmax', False, -1),
+        ('argmin', False, -1)
+    ]
+)
+def test_argminmax_idxminmax_with_datetime64_dtype(op_name, skipna, expected):
+    ser = Series(
+        [datetime(2020, 1, 1), datetime(2020, 1, 2), None],
+        index=['a', 'b', 'c']
+    )
+    result = getattr(ser, op_name)(skipna=skipna)
+    if pd.isna(expected):
+        assert np.isnan(result)
+    else:
+        assert result == expected

From 0cfb621f1d561e862916b22ba96114e98bac9da6 Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Thu, 26 Nov 2020 00:50:25 +0000
Subject: [PATCH 10/21] fixed newbie mistake

---
 pandas/core/series.py                  |  4 ++--
 pandas/tests/series/test_reductions.py | 14 +++++++-------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index 00a246b7ce34e..80d9437267bdd 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2076,7 +2076,7 @@ def idxmin(self, axis=0, skipna=True, *args, **kwargs):
         >>> s.idxmin(skipna=False)
         nan
         """
-        i = self.argmin(axis=None, skipna=skipna, *args, **kwargs)
+        i = self.argmin(None, skipna, *args, *kwargs)
         if i == -1:
             return np.nan
         return self.index[i]
@@ -2146,7 +2146,7 @@ def idxmax(self, axis=0, skipna=True, *args, **kwargs):
         >>> s.idxmax(skipna=False)
         nan
         """
-        i = self.argmax(axis=None, skipna=skipna, *args, **kwargs)
+        i = self.argmax(None, skipna, *args, *kwargs)
         if i == -1:
             return np.nan
         return self.index[i]
diff --git a/pandas/tests/series/test_reductions.py b/pandas/tests/series/test_reductions.py
index b9ef947373a71..ff1a38d6a4085 100644
--- a/pandas/tests/series/test_reductions.py
+++ b/pandas/tests/series/test_reductions.py
@@ -1,6 +1,7 @@
+from datetime import datetime
+
 import numpy as np
 import pytest
-from datetime import datetime
 
 import pandas as pd
 from pandas import MultiIndex, Series
@@ -128,8 +129,8 @@ def test_validate_stat_keepdims():
         ('idxmax', False, np.nan),
         ('idxmin', False, np.nan),
         ('argmax', False, -1),
-        ('argmin', False, -1)
-    ]
+        ('argmin', False, -1),
+    ],
 )
 def test_argminmax_idxminmax(dtype, op_name, skipna, expected):
     ser = Series([1, 2, None], index=['a', 'b', 'c'], dtype=dtype)
@@ -150,13 +151,12 @@ def test_argminmax_idxminmax(dtype, op_name, skipna, expected):
         ('idxmax', False, np.nan),
         ('idxmin', False, np.nan),
         ('argmax', False, -1),
-        ('argmin', False, -1)
-    ]
+        ('argmin', False, -1),
+    ],
 )
 def test_argminmax_idxminmax_with_datetime64_dtype(op_name, skipna, expected):
     ser = Series(
-        [datetime(2020, 1, 1), datetime(2020, 1, 2), None],
-        index=['a', 'b', 'c']
+        [datetime(2020, 1, 1), datetime(2020, 1, 2), None], index=['a', 'b', 'c']
     )
     result = getattr(ser, op_name)(skipna=skipna)
     if pd.isna(expected):

From d4b13ac52fb0faded2163c7b7a3caf05427a4f6d Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Thu, 26 Nov 2020 01:02:43 +0000
Subject: [PATCH 11/21] fixed newbie mistake

---
 pandas/core/series.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index 80d9437267bdd..dafc10d42c702 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2076,7 +2076,7 @@ def idxmin(self, axis=0, skipna=True, *args, **kwargs):
         >>> s.idxmin(skipna=False)
         nan
         """
-        i = self.argmin(None, skipna, *args, *kwargs)
+        i = self.argmin(None, skipna, *args, **kwargs)
         if i == -1:
             return np.nan
         return self.index[i]
@@ -2146,7 +2146,7 @@ def idxmax(self, axis=0, skipna=True, *args, **kwargs):
         >>> s.idxmax(skipna=False)
         nan
         """
-        i = self.argmax(None, skipna, *args, *kwargs)
+        i = self.argmax(None, skipna, *args, **kwargs)
         if i == -1:
             return np.nan
         return self.index[i]

From 5648eb936f7f4f5655bac3c95443c952ac5d150f Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Thu, 26 Nov 2020 02:43:25 +0000
Subject: [PATCH 12/21] used any_numeric_dtype in test

---
 pandas/tests/series/test_reductions.py | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/pandas/tests/series/test_reductions.py b/pandas/tests/series/test_reductions.py
index ff1a38d6a4085..962491dd7bebf 100644
--- a/pandas/tests/series/test_reductions.py
+++ b/pandas/tests/series/test_reductions.py
@@ -118,7 +118,6 @@ def test_validate_stat_keepdims():
         np.sum(ser, keepdims=True)
 
 
-@pytest.mark.parametrize('dtype', ['Int64', 'Float64'])
 @pytest.mark.parametrize(
     "op_name, skipna, expected",
     [
@@ -132,8 +131,8 @@ def test_validate_stat_keepdims():
         ('argmin', False, -1),
     ],
 )
-def test_argminmax_idxminmax(dtype, op_name, skipna, expected):
-    ser = Series([1, 2, None], index=['a', 'b', 'c'], dtype=dtype)
+def test_argminmax_idxminmax(any_numeric_dtype, op_name, skipna, expected):
+    ser = Series([1, 2, None], index=['a', 'b', 'c'], dtype=any_numeric_dtype)
     result = getattr(ser, op_name)(skipna=skipna)
     if pd.isna(expected):
         assert np.isnan(result)

From 9a1b332f9f2ebc457789763f873a89cc8b4c8bb2 Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Thu, 26 Nov 2020 03:17:58 +0000
Subject: [PATCH 13/21] does this solve the pre-commit check failure now?

---
 pandas/tests/series/test_reductions.py | 36 +++++++++++++-------------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/pandas/tests/series/test_reductions.py b/pandas/tests/series/test_reductions.py
index 962491dd7bebf..dc391d3069531 100644
--- a/pandas/tests/series/test_reductions.py
+++ b/pandas/tests/series/test_reductions.py
@@ -121,18 +121,18 @@ def test_validate_stat_keepdims():
 @pytest.mark.parametrize(
     "op_name, skipna, expected",
     [
-        ('idxmax', True, 'b'),
-        ('idxmin', True, 'a'),
-        ('argmax', True, 1),
-        ('argmin', True, 0),
-        ('idxmax', False, np.nan),
-        ('idxmin', False, np.nan),
-        ('argmax', False, -1),
-        ('argmin', False, -1),
+        ("idxmax", True, "b"),
+        ("idxmin", True, "a"),
+        ("argmax", True, 1),
+        ("argmin", True, 0),
+        ("idxmax", False, np.nan),
+        ("idxmin", False, np.nan),
+        ("argmax", False, -1),
+        ("argmin", False, -1),
     ],
 )
 def test_argminmax_idxminmax(any_numeric_dtype, op_name, skipna, expected):
-    ser = Series([1, 2, None], index=['a', 'b', 'c'], dtype=any_numeric_dtype)
+    ser = Series([1, 2, None], index=["a", "b", "c"], dtype=any_numeric_dtype)
     result = getattr(ser, op_name)(skipna=skipna)
     if pd.isna(expected):
         assert np.isnan(result)
@@ -143,19 +143,19 @@ def test_argminmax_idxminmax(any_numeric_dtype, op_name, skipna, expected):
 @pytest.mark.parametrize(
     "op_name, skipna, expected",
     [
-        ('idxmax', True, 'b'),
-        ('idxmin', True, 'a'),
-        ('argmax', True, 1),
-        ('argmin', True, 0),
-        ('idxmax', False, np.nan),
-        ('idxmin', False, np.nan),
-        ('argmax', False, -1),
-        ('argmin', False, -1),
+        ("idxmax", True, "b"),
+        ("idxmin", True, "a"),
+        ("argmax", True, 1),
+        ("argmin", True, 0),
+        ("idxmax", False, np.nan),
+        ("idxmin", False, np.nan),
+        ("argmax", False, -1),
+        ("argmin", False, -1),
     ],
 )
 def test_argminmax_idxminmax_with_datetime64_dtype(op_name, skipna, expected):
     ser = Series(
-        [datetime(2020, 1, 1), datetime(2020, 1, 2), None], index=['a', 'b', 'c']
+        [datetime(2020, 1, 1), datetime(2020, 1, 2), None], index=["a", "b", "c"]
     )
     result = getattr(ser, op_name)(skipna=skipna)
     if pd.isna(expected):

From 9f5e683b846c4c417b0d29ea78348c40f07e83cb Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Thu, 26 Nov 2020 15:25:46 +0000
Subject: [PATCH 14/21] moved EA's skipna logic from Series.argmin/max to
 EA.argmin/max

---
 pandas/core/arrays/base.py | 24 ++++++++++++++++++++----
 pandas/core/base.py        | 10 ++--------
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index bd5cf43e19e9f..dd8a4088c06b7 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -591,13 +591,18 @@ def argsort(
             mask=np.asarray(self.isna()),
         )
 
-    def argmin(self):
+    def argmin(self, skipna: bool = True) -> int:
         """
         Return the index of minimum value.
 
         In case of multiple occurrences of the minimum value, the index
         corresponding to the first occurrence is returned.
 
+        Parameters
+        ----------
+        skipna : bool, default True
+            Exclude NA values when showing the result.
+
         Returns
         -------
         int
@@ -606,15 +611,23 @@ def argmin(self):
         --------
         ExtensionArray.argmax
         """
-        return nargminmax(self, "argmin")
+        if not skipna and self.isna().any():
+            return -1
+        else:
+            return nargminmax(self, "argmin")
 
-    def argmax(self):
+    def argmax(self, skipna: bool = True) -> int:
         """
         Return the index of maximum value.
 
         In case of multiple occurrences of the maximum value, the index
         corresponding to the first occurrence is returned.
 
+        Parameters
+        ----------
+        skipna : bool, default True
+            Exclude NA values when showing the result.
+
         Returns
         -------
         int
@@ -623,7 +636,10 @@ def argmax(self):
         --------
         ExtensionArray.argmin
         """
-        return nargminmax(self, "argmax")
+        if not skipna and self.isna().any():
+            return -1
+        else:
+            return nargminmax(self, "argmax")
 
     def fillna(self, value=None, method=None, limit=None):
         """
diff --git a/pandas/core/base.py b/pandas/core/base.py
index 8b1ee8a04b822..3d0b5e54d1438 100644
--- a/pandas/core/base.py
+++ b/pandas/core/base.py
@@ -720,10 +720,7 @@ def argmax(self, axis=None, skipna: bool = True, *args, **kwargs) -> int:
         skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
 
         if isinstance(delegate, ExtensionArray):
-            if not skipna and isna(delegate).any():
-                return -1
-            else:
-                return delegate.argmax()
+            return delegate.argmax(skipna)
         else:
             return nanops.nanargmax(delegate, skipna=skipna)
 
@@ -778,10 +775,7 @@ def argmin(self, axis=None, skipna=True, *args, **kwargs) -> int:
         skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
 
         if isinstance(delegate, ExtensionArray):
-            if not skipna and isna(delegate).any():
-                return -1
-            else:
-                return delegate.argmin()
+            return delegate.argmin(skipna)
         else:
             return nanops.nanargmin(delegate, skipna=skipna)
 

From e73a3d119ae4d7bf86c039ad2b98c8ade5a721ea Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Fri, 27 Nov 2020 22:07:51 +0000
Subject: [PATCH 15/21] moved EA's skipna logic back to Series

---
 pandas/core/arrays/base.py | 24 ++++--------------------
 pandas/core/base.py        | 10 ++++++++--
 2 files changed, 12 insertions(+), 22 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index dd8a4088c06b7..bd5cf43e19e9f 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -591,18 +591,13 @@ def argsort(
             mask=np.asarray(self.isna()),
         )
 
-    def argmin(self, skipna: bool = True) -> int:
+    def argmin(self):
         """
         Return the index of minimum value.
 
         In case of multiple occurrences of the minimum value, the index
         corresponding to the first occurrence is returned.
 
-        Parameters
-        ----------
-        skipna : bool, default True
-            Exclude NA values when showing the result.
-
         Returns
         -------
         int
@@ -611,23 +606,15 @@ def argmin(self, skipna: bool = True) -> int:
         --------
         ExtensionArray.argmax
         """
-        if not skipna and self.isna().any():
-            return -1
-        else:
-            return nargminmax(self, "argmin")
+        return nargminmax(self, "argmin")
 
-    def argmax(self, skipna: bool = True) -> int:
+    def argmax(self):
         """
         Return the index of maximum value.
 
         In case of multiple occurrences of the maximum value, the index
         corresponding to the first occurrence is returned.
 
-        Parameters
-        ----------
-        skipna : bool, default True
-            Exclude NA values when showing the result.
-
         Returns
         -------
         int
@@ -636,10 +623,7 @@ def argmax(self, skipna: bool = True) -> int:
         --------
         ExtensionArray.argmin
         """
-        if not skipna and self.isna().any():
-            return -1
-        else:
-            return nargminmax(self, "argmax")
+        return nargminmax(self, "argmax")
 
     def fillna(self, value=None, method=None, limit=None):
         """
diff --git a/pandas/core/base.py b/pandas/core/base.py
index 3d0b5e54d1438..8b1ee8a04b822 100644
--- a/pandas/core/base.py
+++ b/pandas/core/base.py
@@ -720,7 +720,10 @@ def argmax(self, axis=None, skipna: bool = True, *args, **kwargs) -> int:
         skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
 
         if isinstance(delegate, ExtensionArray):
-            return delegate.argmax(skipna)
+            if not skipna and isna(delegate).any():
+                return -1
+            else:
+                return delegate.argmax()
         else:
             return nanops.nanargmax(delegate, skipna=skipna)
 
@@ -775,7 +778,10 @@ def argmin(self, axis=None, skipna=True, *args, **kwargs) -> int:
         skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
 
         if isinstance(delegate, ExtensionArray):
-            return delegate.argmin(skipna)
+            if not skipna and isna(delegate).any():
+                return -1
+            else:
+                return delegate.argmin()
         else:
             return nanops.nanargmin(delegate, skipna=skipna)
 

From d78e28ccbbacf48542722ffa9e93a03837485950 Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Fri, 27 Nov 2020 22:15:59 +0000
Subject: [PATCH 16/21] moved EA's skipna logic back to Series

---
 pandas/core/base.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/base.py b/pandas/core/base.py
index 8b1ee8a04b822..afc22a8446dce 100644
--- a/pandas/core/base.py
+++ b/pandas/core/base.py
@@ -720,7 +720,7 @@ def argmax(self, axis=None, skipna: bool = True, *args, **kwargs) -> int:
         skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
 
         if isinstance(delegate, ExtensionArray):
-            if not skipna and isna(delegate).any():
+            if not skipna and delegate.isna().any():
                 return -1
             else:
                 return delegate.argmax()
@@ -778,7 +778,7 @@ def argmin(self, axis=None, skipna=True, *args, **kwargs) -> int:
         skipna = nv.validate_argmin_with_skipna(skipna, args, kwargs)
 
         if isinstance(delegate, ExtensionArray):
-            if not skipna and isna(delegate).any():
+            if not skipna and delegate.isna().any():
                 return -1
             else:
                 return delegate.argmin()

From 66f318785d66f62fc350171f82f8fab442da8f8c Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Sat, 5 Dec 2020 17:23:30 +0000
Subject: [PATCH 17/21] added whatsnew entry and extra tests

---
 pandas/tests/series/test_reductions.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/pandas/tests/series/test_reductions.py b/pandas/tests/series/test_reductions.py
index dc391d3069531..ed9bdb7c343ab 100644
--- a/pandas/tests/series/test_reductions.py
+++ b/pandas/tests/series/test_reductions.py
@@ -162,3 +162,15 @@ def test_argminmax_idxminmax_with_datetime64_dtype(op_name, skipna, expected):
         assert np.isnan(result)
     else:
         assert result == expected
+
+
+def test_github_issues():
+    # GH#36566
+    ser = Series("a", dtype="string").value_counts()
+    assert ser.idxmax() == "a"
+
+    # GH#32749
+    from pandas.tests.extension.decimal import DecimalArray, make_data
+
+    ser = Series(DecimalArray(make_data()[:1]))
+    assert ser.idxmax() == 0

From 6f01069af6e86cf409caa2bdb850ab42011537e1 Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Sat, 5 Dec 2020 19:47:05 +0000
Subject: [PATCH 18/21] moved tests to tests/reductions/rest_reductions.py

---
 pandas/tests/reductions/test_reductions.py | 54 +++++++++++++++++++
 pandas/tests/series/test_reductions.py     | 60 ----------------------
 2 files changed, 54 insertions(+), 60 deletions(-)

diff --git a/pandas/tests/reductions/test_reductions.py b/pandas/tests/reductions/test_reductions.py
index 8c2297699807d..e77357c31dfaa 100644
--- a/pandas/tests/reductions/test_reductions.py
+++ b/pandas/tests/reductions/test_reductions.py
@@ -856,6 +856,16 @@ def test_idxmax(self):
         result = s.idxmin()
         assert result == 1.1
 
+        # GH#36566
+        s = Series("a", dtype="string").value_counts()
+        assert s.idxmax() == "a"
+
+        # GH#32749
+        from pandas.tests.extension.decimal import DecimalArray, make_data
+
+        s = Series(DecimalArray(make_data()[:1]))
+        assert s.idxmax() == 0
+
     def test_all_any(self):
         ts = tm.makeTimeSeries()
         bool_series = ts > 0
@@ -1007,6 +1017,27 @@ def test_idxminmax_with_inf(self):
             assert s.idxmax() == 0
             np.isnan(s.idxmax(skipna=False))
 
+    @pytest.mark.parametrize(
+        "op_name, skipna, expected",
+        [
+            ("idxmax", True, "b"),
+            ("idxmin", True, "a"),
+            ("argmax", True, 1),
+            ("argmin", True, 0),
+            ("idxmax", False, np.nan),
+            ("idxmin", False, np.nan),
+            ("argmax", False, -1),
+            ("argmin", False, -1),
+        ],
+    )
+    def test_argminmax_idxminmax(self, any_numeric_dtype, op_name, skipna, expected):
+        s = Series([1, 2, None], index=["a", "b", "c"], dtype=any_numeric_dtype)
+        result = getattr(s, op_name)(skipna=skipna)
+        if pd.isna(expected):
+            assert np.isnan(result)
+        else:
+            assert result == expected
+
 
 class TestDatetime64SeriesReductions:
     # Note: the name TestDatetime64SeriesReductions indicates these tests
@@ -1072,6 +1103,29 @@ def test_min_max_series(self):
         assert isinstance(result, Timestamp)
         assert result == exp
 
+    @pytest.mark.parametrize(
+        "op_name, skipna, expected",
+        [
+            ("idxmax", True, "b"),
+            ("idxmin", True, "a"),
+            ("argmax", True, 1),
+            ("argmin", True, 0),
+            ("idxmax", False, np.nan),
+            ("idxmin", False, np.nan),
+            ("argmax", False, -1),
+            ("argmin", False, -1),
+        ],
+    )
+    def test_argminmax_idxminmax(self, op_name, skipna, expected):
+        s = Series(
+            [datetime(2020, 1, 1), datetime(2020, 1, 2), None], index=["a", "b", "c"]
+        )
+        result = getattr(s, op_name)(skipna=skipna)
+        if pd.isna(expected):
+            assert np.isnan(result)
+        else:
+            assert result == expected
+
 
 class TestCategoricalSeriesReductions:
     # Note: the name TestCategoricalSeriesReductions indicates these tests
diff --git a/pandas/tests/series/test_reductions.py b/pandas/tests/series/test_reductions.py
index ed9bdb7c343ab..c3c58f29fcbf6 100644
--- a/pandas/tests/series/test_reductions.py
+++ b/pandas/tests/series/test_reductions.py
@@ -1,5 +1,3 @@
-from datetime import datetime
-
 import numpy as np
 import pytest
 
@@ -116,61 +114,3 @@ def test_validate_stat_keepdims():
     )
     with pytest.raises(ValueError, match=msg):
         np.sum(ser, keepdims=True)
-
-
-@pytest.mark.parametrize(
-    "op_name, skipna, expected",
-    [
-        ("idxmax", True, "b"),
-        ("idxmin", True, "a"),
-        ("argmax", True, 1),
-        ("argmin", True, 0),
-        ("idxmax", False, np.nan),
-        ("idxmin", False, np.nan),
-        ("argmax", False, -1),
-        ("argmin", False, -1),
-    ],
-)
-def test_argminmax_idxminmax(any_numeric_dtype, op_name, skipna, expected):
-    ser = Series([1, 2, None], index=["a", "b", "c"], dtype=any_numeric_dtype)
-    result = getattr(ser, op_name)(skipna=skipna)
-    if pd.isna(expected):
-        assert np.isnan(result)
-    else:
-        assert result == expected
-
-
-@pytest.mark.parametrize(
-    "op_name, skipna, expected",
-    [
-        ("idxmax", True, "b"),
-        ("idxmin", True, "a"),
-        ("argmax", True, 1),
-        ("argmin", True, 0),
-        ("idxmax", False, np.nan),
-        ("idxmin", False, np.nan),
-        ("argmax", False, -1),
-        ("argmin", False, -1),
-    ],
-)
-def test_argminmax_idxminmax_with_datetime64_dtype(op_name, skipna, expected):
-    ser = Series(
-        [datetime(2020, 1, 1), datetime(2020, 1, 2), None], index=["a", "b", "c"]
-    )
-    result = getattr(ser, op_name)(skipna=skipna)
-    if pd.isna(expected):
-        assert np.isnan(result)
-    else:
-        assert result == expected
-
-
-def test_github_issues():
-    # GH#36566
-    ser = Series("a", dtype="string").value_counts()
-    assert ser.idxmax() == "a"
-
-    # GH#32749
-    from pandas.tests.extension.decimal import DecimalArray, make_data
-
-    ser = Series(DecimalArray(make_data()[:1]))
-    assert ser.idxmax() == 0

From 3540797bb1ff820e2d6385e9f901ecd37364b23d Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Mon, 28 Dec 2020 23:23:41 +0000
Subject: [PATCH 19/21] added 1.3 whatsnew entry

---
 doc/source/whatsnew/v1.3.0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v1.3.0.rst b/doc/source/whatsnew/v1.3.0.rst
index 35785613fb1e2..464e89abc6270 100644
--- a/doc/source/whatsnew/v1.3.0.rst
+++ b/doc/source/whatsnew/v1.3.0.rst
@@ -295,7 +295,7 @@ Sparse
 ExtensionArray
 ^^^^^^^^^^^^^^
 
--
+- Fixed bug where :meth:`Series.idxmax`, :meth:`Series.idxmin` and ``argmax/min`` fail when the underlying data is :class:`ExtensionArray` (:issue:`32749`, :issue:`33719`, :issue:`36566`)
 -
 
 Other

From 6d0b68ee4baa88db453ec6ef2139c4b8554c7078 Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Wed, 30 Dec 2020 19:21:10 +0000
Subject: [PATCH 20/21] moved and restructured tests

---
 pandas/core/series.py                         |  4 +-
 pandas/tests/extension/base/__init__.py       |  1 +
 pandas/tests/extension/base/reduce.py         |  8 +++
 .../tests/extension/decimal/test_decimal.py   |  4 ++
 pandas/tests/extension/test_boolean.py        |  4 ++
 pandas/tests/extension/test_datetime.py       | 14 +++++
 pandas/tests/extension/test_floating.py       |  4 ++
 pandas/tests/extension/test_integer.py        |  4 ++
 pandas/tests/extension/test_numpy.py          |  5 ++
 pandas/tests/reductions/test_reductions.py    | 54 -------------------
 10 files changed, 46 insertions(+), 56 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index dafc10d42c702..9fe0e8e356252 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2076,7 +2076,7 @@ def idxmin(self, axis=0, skipna=True, *args, **kwargs):
         >>> s.idxmin(skipna=False)
         nan
         """
-        i = self.argmin(None, skipna, *args, **kwargs)
+        i = self.argmin(None, skipna=skipna)
         if i == -1:
             return np.nan
         return self.index[i]
@@ -2146,7 +2146,7 @@ def idxmax(self, axis=0, skipna=True, *args, **kwargs):
         >>> s.idxmax(skipna=False)
         nan
         """
-        i = self.argmax(None, skipna, *args, **kwargs)
+        i = self.argmax(None, skipna=skipna)
         if i == -1:
             return np.nan
         return self.index[i]
diff --git a/pandas/tests/extension/base/__init__.py b/pandas/tests/extension/base/__init__.py
index 323cb843b2d74..63228cf752a09 100644
--- a/pandas/tests/extension/base/__init__.py
+++ b/pandas/tests/extension/base/__init__.py
@@ -58,6 +58,7 @@ class TestMyDtype(BaseDtypeTests):
 )
 from .printing import BasePrintingTests  # noqa
 from .reduce import (  # noqa
+    BaseArgReduceTests,
     BaseBooleanReduceTests,
     BaseNoReduceTests,
     BaseNumericReduceTests,
diff --git a/pandas/tests/extension/base/reduce.py b/pandas/tests/extension/base/reduce.py
index 55f8aca1b8ae0..2c587ff83be79 100644
--- a/pandas/tests/extension/base/reduce.py
+++ b/pandas/tests/extension/base/reduce.py
@@ -68,3 +68,11 @@ def test_reduce_series(self, data, all_boolean_reductions, skipna):
         op_name = all_boolean_reductions
         s = pd.Series(data)
         self.check_reduce(s, op_name, skipna)
+
+
+class BaseArgReduceTests(BaseReduceTests):
+    @pytest.mark.parametrize("skipna", [True, False])
+    @pytest.mark.parametrize("op_name", ["argmin", "argmax", "idxmin", "idxmax"])
+    def test_reduce_series(self, data, op_name, skipna):
+        s = pd.Series(data)
+        self.check_reduce(s, op_name, skipna)
diff --git a/pandas/tests/extension/decimal/test_decimal.py b/pandas/tests/extension/decimal/test_decimal.py
index 233b658d29782..5a5a4824b1394 100644
--- a/pandas/tests/extension/decimal/test_decimal.py
+++ b/pandas/tests/extension/decimal/test_decimal.py
@@ -166,6 +166,10 @@ class TestBooleanReduce(Reduce, base.BaseBooleanReduceTests):
     pass
 
 
+class TestArgReduce(base.BaseArgReduceTests):
+    pass
+
+
 class TestMethods(BaseDecimal, base.BaseMethodsTests):
     @pytest.mark.parametrize("dropna", [True, False])
     @pytest.mark.xfail(reason="value_counts not implemented yet.")
diff --git a/pandas/tests/extension/test_boolean.py b/pandas/tests/extension/test_boolean.py
index ced7ea9261310..81a42a6ecd392 100644
--- a/pandas/tests/extension/test_boolean.py
+++ b/pandas/tests/extension/test_boolean.py
@@ -381,6 +381,10 @@ class TestBooleanReduce(base.BaseBooleanReduceTests):
     pass
 
 
+class TestArgReduce(base.BaseArgReduceTests):
+    pass
+
+
 class TestPrinting(base.BasePrintingTests):
     pass
 
diff --git a/pandas/tests/extension/test_datetime.py b/pandas/tests/extension/test_datetime.py
index 0fde1e8a2fdb8..4a5558bb0c45d 100644
--- a/pandas/tests/extension/test_datetime.py
+++ b/pandas/tests/extension/test_datetime.py
@@ -4,6 +4,7 @@
 from pandas.core.dtypes.dtypes import DatetimeTZDtype
 
 import pandas as pd
+import pandas._testing as tm
 from pandas.core.arrays import DatetimeArray
 from pandas.tests.extension import base
 
@@ -223,3 +224,16 @@ class TestGroupby(BaseDatetimeTests, base.BaseGroupbyTests):
 
 class TestPrinting(BaseDatetimeTests, base.BasePrintingTests):
     pass
+
+
+class TestArgReduce(base.BaseArgReduceTests):
+    def check_reduce(self, s, op_name, skipna):
+        result = getattr(s, op_name)(skipna=skipna)
+        if not skipna and s.isna().any():
+            if op_name in ["argmin", "argmax"]:
+                expected = -1
+            else:
+                expected = np.nan
+        else:
+            expected = getattr(s.dropna().astype("int64"), op_name)(skipna=skipna)
+        tm.assert_almost_equal(result, expected)
diff --git a/pandas/tests/extension/test_floating.py b/pandas/tests/extension/test_floating.py
index c08c31e90fecc..e9275686eb55e 100644
--- a/pandas/tests/extension/test_floating.py
+++ b/pandas/tests/extension/test_floating.py
@@ -215,6 +215,10 @@ class TestBooleanReduce(base.BaseBooleanReduceTests):
     pass
 
 
+class TestArgReduce(base.BaseArgReduceTests):
+    pass
+
+
 class TestPrinting(base.BasePrintingTests):
     pass
 
diff --git a/pandas/tests/extension/test_integer.py b/pandas/tests/extension/test_integer.py
index 99a32203053c6..a4c260686002c 100644
--- a/pandas/tests/extension/test_integer.py
+++ b/pandas/tests/extension/test_integer.py
@@ -249,6 +249,10 @@ class TestBooleanReduce(base.BaseBooleanReduceTests):
     pass
 
 
+class TestArgReduce(base.BaseArgReduceTests):
+    pass
+
+
 class TestPrinting(base.BasePrintingTests):
     pass
 
diff --git a/pandas/tests/extension/test_numpy.py b/pandas/tests/extension/test_numpy.py
index 29790d14f93cc..80d3406a3ccaf 100644
--- a/pandas/tests/extension/test_numpy.py
+++ b/pandas/tests/extension/test_numpy.py
@@ -315,6 +315,11 @@ class TestBooleanReduce(BaseNumPyTests, base.BaseBooleanReduceTests):
     pass
 
 
+@skip_nested
+class TestArgReduce(base.BaseArgReduceTests):
+    pass
+
+
 class TestMissing(BaseNumPyTests, base.BaseMissingTests):
     @skip_nested
     def test_fillna_scalar(self, data_missing):
diff --git a/pandas/tests/reductions/test_reductions.py b/pandas/tests/reductions/test_reductions.py
index e77357c31dfaa..8c2297699807d 100644
--- a/pandas/tests/reductions/test_reductions.py
+++ b/pandas/tests/reductions/test_reductions.py
@@ -856,16 +856,6 @@ def test_idxmax(self):
         result = s.idxmin()
         assert result == 1.1
 
-        # GH#36566
-        s = Series("a", dtype="string").value_counts()
-        assert s.idxmax() == "a"
-
-        # GH#32749
-        from pandas.tests.extension.decimal import DecimalArray, make_data
-
-        s = Series(DecimalArray(make_data()[:1]))
-        assert s.idxmax() == 0
-
     def test_all_any(self):
         ts = tm.makeTimeSeries()
         bool_series = ts > 0
@@ -1017,27 +1007,6 @@ def test_idxminmax_with_inf(self):
             assert s.idxmax() == 0
             np.isnan(s.idxmax(skipna=False))
 
-    @pytest.mark.parametrize(
-        "op_name, skipna, expected",
-        [
-            ("idxmax", True, "b"),
-            ("idxmin", True, "a"),
-            ("argmax", True, 1),
-            ("argmin", True, 0),
-            ("idxmax", False, np.nan),
-            ("idxmin", False, np.nan),
-            ("argmax", False, -1),
-            ("argmin", False, -1),
-        ],
-    )
-    def test_argminmax_idxminmax(self, any_numeric_dtype, op_name, skipna, expected):
-        s = Series([1, 2, None], index=["a", "b", "c"], dtype=any_numeric_dtype)
-        result = getattr(s, op_name)(skipna=skipna)
-        if pd.isna(expected):
-            assert np.isnan(result)
-        else:
-            assert result == expected
-
 
 class TestDatetime64SeriesReductions:
     # Note: the name TestDatetime64SeriesReductions indicates these tests
@@ -1103,29 +1072,6 @@ def test_min_max_series(self):
         assert isinstance(result, Timestamp)
         assert result == exp
 
-    @pytest.mark.parametrize(
-        "op_name, skipna, expected",
-        [
-            ("idxmax", True, "b"),
-            ("idxmin", True, "a"),
-            ("argmax", True, 1),
-            ("argmin", True, 0),
-            ("idxmax", False, np.nan),
-            ("idxmin", False, np.nan),
-            ("argmax", False, -1),
-            ("argmin", False, -1),
-        ],
-    )
-    def test_argminmax_idxminmax(self, op_name, skipna, expected):
-        s = Series(
-            [datetime(2020, 1, 1), datetime(2020, 1, 2), None], index=["a", "b", "c"]
-        )
-        result = getattr(s, op_name)(skipna=skipna)
-        if pd.isna(expected):
-            assert np.isnan(result)
-        else:
-            assert result == expected
-
 
 class TestCategoricalSeriesReductions:
     # Note: the name TestCategoricalSeriesReductions indicates these tests

From 4f6d11152b2753598adb27efb160b59c55cf8bce Mon Sep 17 00:00:00 2001
From: jy3515 <yejunyuantony@gmail.com>
Date: Thu, 31 Dec 2020 00:49:13 +0000
Subject: [PATCH 21/21] moved tests to pandas/tests/extensions/methods.py

---
 pandas/tests/extension/base/__init__.py       |  1 -
 pandas/tests/extension/base/methods.py        | 21 +++++++++++++++++++
 pandas/tests/extension/base/reduce.py         |  8 -------
 .../tests/extension/decimal/test_decimal.py   |  4 ----
 pandas/tests/extension/test_boolean.py        |  4 ----
 pandas/tests/extension/test_datetime.py       | 14 -------------
 pandas/tests/extension/test_floating.py       |  4 ----
 pandas/tests/extension/test_integer.py        |  4 ----
 pandas/tests/extension/test_numpy.py          |  5 -----
 9 files changed, 21 insertions(+), 44 deletions(-)

diff --git a/pandas/tests/extension/base/__init__.py b/pandas/tests/extension/base/__init__.py
index 63228cf752a09..323cb843b2d74 100644
--- a/pandas/tests/extension/base/__init__.py
+++ b/pandas/tests/extension/base/__init__.py
@@ -58,7 +58,6 @@ class TestMyDtype(BaseDtypeTests):
 )
 from .printing import BasePrintingTests  # noqa
 from .reduce import (  # noqa
-    BaseArgReduceTests,
     BaseBooleanReduceTests,
     BaseNoReduceTests,
     BaseNumericReduceTests,
diff --git a/pandas/tests/extension/base/methods.py b/pandas/tests/extension/base/methods.py
index 1cc03d4f4f2bd..472e783c977f0 100644
--- a/pandas/tests/extension/base/methods.py
+++ b/pandas/tests/extension/base/methods.py
@@ -107,6 +107,27 @@ def test_argmin_argmax_all_na(self, method, data, na_value):
         with pytest.raises(ValueError, match=err_msg):
             getattr(data_na, method)()
 
+    @pytest.mark.parametrize(
+        "op_name, skipna, expected",
+        [
+            ("idxmax", True, 0),
+            ("idxmin", True, 2),
+            ("argmax", True, 0),
+            ("argmin", True, 2),
+            ("idxmax", False, np.nan),
+            ("idxmin", False, np.nan),
+            ("argmax", False, -1),
+            ("argmin", False, -1),
+        ],
+    )
+    def test_argreduce_series(
+        self, data_missing_for_sorting, op_name, skipna, expected
+    ):
+        # data_missing_for_sorting -> [B, NA, A] with A < B and NA missing.
+        ser = pd.Series(data_missing_for_sorting)
+        result = getattr(ser, op_name)(skipna=skipna)
+        tm.assert_almost_equal(result, expected)
+
     @pytest.mark.parametrize(
         "na_position, expected",
         [
diff --git a/pandas/tests/extension/base/reduce.py b/pandas/tests/extension/base/reduce.py
index 2c587ff83be79..55f8aca1b8ae0 100644
--- a/pandas/tests/extension/base/reduce.py
+++ b/pandas/tests/extension/base/reduce.py
@@ -68,11 +68,3 @@ def test_reduce_series(self, data, all_boolean_reductions, skipna):
         op_name = all_boolean_reductions
         s = pd.Series(data)
         self.check_reduce(s, op_name, skipna)
-
-
-class BaseArgReduceTests(BaseReduceTests):
-    @pytest.mark.parametrize("skipna", [True, False])
-    @pytest.mark.parametrize("op_name", ["argmin", "argmax", "idxmin", "idxmax"])
-    def test_reduce_series(self, data, op_name, skipna):
-        s = pd.Series(data)
-        self.check_reduce(s, op_name, skipna)
diff --git a/pandas/tests/extension/decimal/test_decimal.py b/pandas/tests/extension/decimal/test_decimal.py
index 5a5a4824b1394..233b658d29782 100644
--- a/pandas/tests/extension/decimal/test_decimal.py
+++ b/pandas/tests/extension/decimal/test_decimal.py
@@ -166,10 +166,6 @@ class TestBooleanReduce(Reduce, base.BaseBooleanReduceTests):
     pass
 
 
-class TestArgReduce(base.BaseArgReduceTests):
-    pass
-
-
 class TestMethods(BaseDecimal, base.BaseMethodsTests):
     @pytest.mark.parametrize("dropna", [True, False])
     @pytest.mark.xfail(reason="value_counts not implemented yet.")
diff --git a/pandas/tests/extension/test_boolean.py b/pandas/tests/extension/test_boolean.py
index 81a42a6ecd392..ced7ea9261310 100644
--- a/pandas/tests/extension/test_boolean.py
+++ b/pandas/tests/extension/test_boolean.py
@@ -381,10 +381,6 @@ class TestBooleanReduce(base.BaseBooleanReduceTests):
     pass
 
 
-class TestArgReduce(base.BaseArgReduceTests):
-    pass
-
-
 class TestPrinting(base.BasePrintingTests):
     pass
 
diff --git a/pandas/tests/extension/test_datetime.py b/pandas/tests/extension/test_datetime.py
index 4a5558bb0c45d..0fde1e8a2fdb8 100644
--- a/pandas/tests/extension/test_datetime.py
+++ b/pandas/tests/extension/test_datetime.py
@@ -4,7 +4,6 @@
 from pandas.core.dtypes.dtypes import DatetimeTZDtype
 
 import pandas as pd
-import pandas._testing as tm
 from pandas.core.arrays import DatetimeArray
 from pandas.tests.extension import base
 
@@ -224,16 +223,3 @@ class TestGroupby(BaseDatetimeTests, base.BaseGroupbyTests):
 
 class TestPrinting(BaseDatetimeTests, base.BasePrintingTests):
     pass
-
-
-class TestArgReduce(base.BaseArgReduceTests):
-    def check_reduce(self, s, op_name, skipna):
-        result = getattr(s, op_name)(skipna=skipna)
-        if not skipna and s.isna().any():
-            if op_name in ["argmin", "argmax"]:
-                expected = -1
-            else:
-                expected = np.nan
-        else:
-            expected = getattr(s.dropna().astype("int64"), op_name)(skipna=skipna)
-        tm.assert_almost_equal(result, expected)
diff --git a/pandas/tests/extension/test_floating.py b/pandas/tests/extension/test_floating.py
index e9275686eb55e..c08c31e90fecc 100644
--- a/pandas/tests/extension/test_floating.py
+++ b/pandas/tests/extension/test_floating.py
@@ -215,10 +215,6 @@ class TestBooleanReduce(base.BaseBooleanReduceTests):
     pass
 
 
-class TestArgReduce(base.BaseArgReduceTests):
-    pass
-
-
 class TestPrinting(base.BasePrintingTests):
     pass
 
diff --git a/pandas/tests/extension/test_integer.py b/pandas/tests/extension/test_integer.py
index a4c260686002c..99a32203053c6 100644
--- a/pandas/tests/extension/test_integer.py
+++ b/pandas/tests/extension/test_integer.py
@@ -249,10 +249,6 @@ class TestBooleanReduce(base.BaseBooleanReduceTests):
     pass
 
 
-class TestArgReduce(base.BaseArgReduceTests):
-    pass
-
-
 class TestPrinting(base.BasePrintingTests):
     pass
 
diff --git a/pandas/tests/extension/test_numpy.py b/pandas/tests/extension/test_numpy.py
index 80d3406a3ccaf..29790d14f93cc 100644
--- a/pandas/tests/extension/test_numpy.py
+++ b/pandas/tests/extension/test_numpy.py
@@ -315,11 +315,6 @@ class TestBooleanReduce(BaseNumPyTests, base.BaseBooleanReduceTests):
     pass
 
 
-@skip_nested
-class TestArgReduce(base.BaseArgReduceTests):
-    pass
-
-
 class TestMissing(BaseNumPyTests, base.BaseMissingTests):
     @skip_nested
     def test_fillna_scalar(self, data_missing):