From 86a3f1c12a97f5f43a26b73e464ab797a62b61f8 Mon Sep 17 00:00:00 2001
From: Patrick Hoefler <patrick_hoefler@gmx.net>
Date: Sat, 5 Nov 2022 22:00:21 +0100
Subject: [PATCH 1/3] CLN: Deduplicate code in duplicated

---
 pandas/_libs/hashtable_func_helper.pxi.in | 26 ++++++-----------------
 1 file changed, 7 insertions(+), 19 deletions(-)

diff --git a/pandas/_libs/hashtable_func_helper.pxi.in b/pandas/_libs/hashtable_func_helper.pxi.in
index 68e253fd03620..331cb9324d690 100644
--- a/pandas/_libs/hashtable_func_helper.pxi.in
+++ b/pandas/_libs/hashtable_func_helper.pxi.in
@@ -141,32 +141,19 @@ cdef duplicated_{{dtype}}(const {{dtype}}_t[:] values, object keep='first', cons
     if keep not in ('last', 'first', False):
         raise ValueError('keep must be either "first", "last" or False')
 
-    if keep == 'last':
+    {{for cond, keep in [('if', '"last"'), ('elif', '"first"')]}}
+    {{cond}} keep == {{keep}}:
         {{if dtype == 'object'}}
         if True:
         {{else}}
         with nogil:
         {{endif}}
+            {{if keep == 'last'}}
             for i in range(n - 1, -1, -1):
-                # equivalent: range(n)[::-1], which cython doesn't like in nogil
-                if uses_mask and mask[i]:
-                    if seen_na:
-                        out[i] = True
-                    else:
-                        out[i] = False
-                        seen_na = True
-                else:
-                    value = {{to_c_type}}(values[i])
-                    kh_put_{{ttype}}(table, value, &ret)
-                    out[i] = ret == 0
-
-    elif keep == 'first':
-        {{if dtype == 'object'}}
-        if True:
-        {{else}}
-        with nogil:
-        {{endif}}
+            {{else}}
             for i in range(n):
+            {{endif}}
+                # equivalent: range(n)[::-1], which cython doesn't like in nogil
                 if uses_mask and mask[i]:
                     if seen_na:
                         out[i] = True
@@ -177,6 +164,7 @@ cdef duplicated_{{dtype}}(const {{dtype}}_t[:] values, object keep='first', cons
                     value = {{to_c_type}}(values[i])
                     kh_put_{{ttype}}(table, value, &ret)
                     out[i] = ret == 0
+    {{endfor}}
 
     else:
         {{if dtype == 'object'}}

From 35375ddf96b01ae143fc726b0adf5e0de82a0ca9 Mon Sep 17 00:00:00 2001
From: Patrick Hoefler <patrick_hoefler@gmx.net>
Date: Sat, 5 Nov 2022 22:01:45 +0100
Subject: [PATCH 2/3] Clean

---
 pandas/_libs/hashtable_func_helper.pxi.in | 1 -
 1 file changed, 1 deletion(-)

diff --git a/pandas/_libs/hashtable_func_helper.pxi.in b/pandas/_libs/hashtable_func_helper.pxi.in
index 331cb9324d690..d9f36357976de 100644
--- a/pandas/_libs/hashtable_func_helper.pxi.in
+++ b/pandas/_libs/hashtable_func_helper.pxi.in
@@ -153,7 +153,6 @@ cdef duplicated_{{dtype}}(const {{dtype}}_t[:] values, object keep='first', cons
             {{else}}
             for i in range(n):
             {{endif}}
-                # equivalent: range(n)[::-1], which cython doesn't like in nogil
                 if uses_mask and mask[i]:
                     if seen_na:
                         out[i] = True

From 0898ba8e80f9e53eb05c046334c1f2493e806b4d Mon Sep 17 00:00:00 2001
From: Patrick Hoefler <patrick_hoefler@gmx.net>
Date: Sat, 5 Nov 2022 22:03:23 +0100
Subject: [PATCH 3/3] Fix

---
 pandas/_libs/hashtable_func_helper.pxi.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/_libs/hashtable_func_helper.pxi.in b/pandas/_libs/hashtable_func_helper.pxi.in
index d9f36357976de..b9cf6011481af 100644
--- a/pandas/_libs/hashtable_func_helper.pxi.in
+++ b/pandas/_libs/hashtable_func_helper.pxi.in
@@ -148,7 +148,7 @@ cdef duplicated_{{dtype}}(const {{dtype}}_t[:] values, object keep='first', cons
         {{else}}
         with nogil:
         {{endif}}
-            {{if keep == 'last'}}
+            {{if keep == '"last"'}}
             for i in range(n - 1, -1, -1):
             {{else}}
             for i in range(n):