From e780538e1ed781be1cfc12a161d414021051bb7e Mon Sep 17 00:00:00 2001
From: MomIsBestFriend <>
Date: Mon, 6 Apr 2020 13:26:20 +0300
Subject: [PATCH 1/3] CLN: Added static types for `pandas/_libs/reduction.pyx`

---
 pandas/_libs/reduction.pyx | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/pandas/_libs/reduction.pyx b/pandas/_libs/reduction.pyx
index 9f8579606014a..98452b1a2cb27 100644
--- a/pandas/_libs/reduction.pyx
+++ b/pandas/_libs/reduction.pyx
@@ -36,7 +36,12 @@ cdef class Reducer:
         object dummy, f, labels, typ, ityp, index
         ndarray arr
 
-    def __init__(self, ndarray arr, object f, axis=1, dummy=None, labels=None):
+    def __init__(
+        self, ndarray arr, object f, int axis=1, object dummy=None, object labels=None
+    ):
+        cdef:
+            Py_ssize_t n, k
+
         n, k = (<object>arr).shape
 
         if axis == 0:
@@ -60,7 +65,7 @@ cdef class Reducer:
         self.dummy, self.typ, self.index, self.ityp = self._check_dummy(
             dummy=dummy)
 
-    cdef _check_dummy(self, dummy=None):
+    cdef _check_dummy(self, object dummy=None):
         cdef:
             object index = None, typ = None, ityp = None
 
@@ -147,7 +152,7 @@ cdef class Reducer:
 
 
 cdef class _BaseGrouper:
-    cdef _check_dummy(self, dummy):
+    cdef _check_dummy(self, ndarray dummy):
         # both values and index must be an ndarray!
 
         values = dummy.values
@@ -190,13 +195,16 @@ cdef class _BaseGrouper:
         """
         Call self.f on our new group, then update to the next group.
         """
+        cdef:
+            object res
+
         cached_ityp._engine.clear_mapping()
         res = self.f(cached_typ)
         res = _extract_result(res)
         if not initialized:
             # On the first pass, we check the output shape to see
             #  if this looks like a reduction.
-            initialized = 1
+            initialized = True
             _check_result_array(res, len(self.dummy_arr))
 
         islider.advance(group_size)
@@ -535,6 +543,9 @@ cdef class BlockSlider:
         char **base_ptrs
 
     def __init__(self, frame):
+        cdef:
+            Py_ssize_t i, block
+
         self.frame = frame
         self.dummy = frame[:0]
         self.index = self.dummy.index

From f08a827c365cd831ba8424831e4d97749bf2cdba Mon Sep 17 00:00:00 2001
From: MomIsBestFriend <>
Date: Mon, 6 Apr 2020 14:02:04 +0300
Subject: [PATCH 2/3] Fixed errors

---
 pandas/_libs/reduction.pyx | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pandas/_libs/reduction.pyx b/pandas/_libs/reduction.pyx
index 98452b1a2cb27..03813e410e7ab 100644
--- a/pandas/_libs/reduction.pyx
+++ b/pandas/_libs/reduction.pyx
@@ -542,9 +542,10 @@ cdef class BlockSlider:
     cdef:
         char **base_ptrs
 
-    def __init__(self, frame):
+    def __init__(self, object frame):
         cdef:
-            Py_ssize_t i, block
+            Py_ssize_t i
+            object b
 
         self.frame = frame
         self.dummy = frame[:0]

From ceca15442b4f5027181bb9c1b352914013f8cd7a Mon Sep 17 00:00:00 2001
From: MomIsBestFriend <>
Date: Mon, 6 Apr 2020 14:46:55 +0300
Subject: [PATCH 3/3] Fixed more errors

---
 pandas/_libs/reduction.pyx | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/_libs/reduction.pyx b/pandas/_libs/reduction.pyx
index 03813e410e7ab..4a9c89848a9d8 100644
--- a/pandas/_libs/reduction.pyx
+++ b/pandas/_libs/reduction.pyx
@@ -152,7 +152,7 @@ cdef class Reducer:
 
 
 cdef class _BaseGrouper:
-    cdef _check_dummy(self, ndarray dummy):
+    cdef _check_dummy(self, object dummy):
         # both values and index must be an ndarray!
 
         values = dummy.values