From b49bda489545a23b95437ca83e466db68bc92061 Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Sat, 6 Jul 2019 15:14:02 -0700
Subject: [PATCH 1/9] move away from runtime imports

---
 pandas/core/computation/expressions.py |  7 +++----
 pandas/core/ops/__init__.py            | 18 +++++++-----------
 2 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/pandas/core/computation/expressions.py b/pandas/core/computation/expressions.py
index dc4e6e85f6e7d..ea61467080291 100644
--- a/pandas/core/computation/expressions.py
+++ b/pandas/core/computation/expressions.py
@@ -12,9 +12,10 @@
 
 from pandas._config import get_option
 
+from pandas._libs.lib import values_from_object
+
 from pandas.core.dtypes.generic import ABCDataFrame
 
-import pandas.core.common as com
 from pandas.core.computation.check import _NUMEXPR_INSTALLED
 
 if _NUMEXPR_INSTALLED:
@@ -129,9 +130,7 @@ def _evaluate_numexpr(op, op_str, a, b, truediv=True, reversed=False, **eval_kwa
 
 def _where_standard(cond, a, b):
     return np.where(
-        com.values_from_object(cond),
-        com.values_from_object(a),
-        com.values_from_object(b),
+        values_from_object(cond), values_from_object(a), values_from_object(b)
     )
 
 
diff --git a/pandas/core/ops/__init__.py b/pandas/core/ops/__init__.py
index df2907bf591dd..4f88b12fcd647 100644
--- a/pandas/core/ops/__init__.py
+++ b/pandas/core/ops/__init__.py
@@ -11,7 +11,7 @@
 
 import numpy as np
 
-from pandas._libs import lib, ops as libops
+from pandas._libs import Timedelta, Timestamp, lib, ops as libops
 from pandas.errors import NullFrequencyError
 from pandas.util._decorators import Appender
 
@@ -49,6 +49,7 @@
 import pandas as pd
 from pandas._typing import ArrayLike
 import pandas.core.common as com
+from pandas.core.computation import expressions
 
 from . import missing
 from .roperator import (  # noqa:F401
@@ -86,7 +87,7 @@ def get_op_result_name(left, right):
         Usually a string
     """
     # `left` is always a pd.Series when called from within ops
-    if isinstance(right, (ABCSeries, pd.Index)):
+    if isinstance(right, (ABCSeries, ABCIndexClass)):
         name = _maybe_match_name(left, right)
     else:
         name = left.name
@@ -150,14 +151,14 @@ def maybe_upcast_for_op(obj):
         # GH#22390  cast up to Timedelta to rely on Timedelta
         # implementation; otherwise operation against numeric-dtype
         # raises TypeError
-        return pd.Timedelta(obj)
+        return Timedelta(obj)
     elif isinstance(obj, np.timedelta64) and not isna(obj):
         # In particular non-nanosecond timedelta64 needs to be cast to
         #  nanoseconds, or else we get undesired behavior like
         #  np.timedelta64(3, 'D') / 2 == np.timedelta64(1, 'D')
         # The isna check is to avoid casting timedelta64("NaT"), which would
         #  return NaT and incorrectly be treated as a datetime-NaT.
-        return pd.Timedelta(obj)
+        return Timedelta(obj)
     elif isinstance(obj, np.ndarray) and is_timedelta64_dtype(obj):
         # GH#22390 Unfortunately we need to special-case right-hand
         # timedelta64 dtypes because numpy casts integer dtypes to
@@ -1253,7 +1254,6 @@ def dispatch_to_series(left, right, func, str_rep=None, axis=None):
     """
     # Note: we use iloc to access columns for compat with cases
     #       with non-unique columns.
-    import pandas.core.computation.expressions as expressions
 
     right = lib.item_from_zerodim(right)
     if lib.is_scalar(right) or np.ndim(right) == 0:
@@ -1661,8 +1661,6 @@ def na_op(x, y):
         ------
         TypeError : invalid operation
         """
-        import pandas.core.computation.expressions as expressions
-
         try:
             result = expressions.evaluate(op, str_rep, x, y, **eval_kwargs)
         except TypeError:
@@ -1849,7 +1847,7 @@ def wrapper(self, other, axis=None):
                     )
                 msg = "\n".join(textwrap.wrap(msg.format(future=future)))
                 warnings.warn(msg, FutureWarning, stacklevel=2)
-                other = pd.Timestamp(other)
+                other = Timestamp(other)
 
             res_values = dispatch_to_index_op(op, self, other, pd.DatetimeIndex)
 
@@ -1875,7 +1873,7 @@ def wrapper(self, other, axis=None):
                 res_values, index=self.index, name=res_name
             ).rename(res_name)
 
-        elif isinstance(other, (np.ndarray, pd.Index)):
+        elif isinstance(other, (np.ndarray, ABCIndexClass)):
             # do not check length of zerodim array
             # as it will broadcast
             if other.ndim != 0 and len(self) != len(other):
@@ -2143,8 +2141,6 @@ def _arith_method_FRAME(cls, op, special):
     default_axis = _get_frame_op_default_axis(op_name)
 
     def na_op(x, y):
-        import pandas.core.computation.expressions as expressions
-
         try:
             result = expressions.evaluate(op, str_rep, x, y, **eval_kwargs)
         except TypeError:

From a0fc709ac2e2bcb6d3e726f74cacaf59def41727 Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Sun, 7 Jul 2019 11:35:44 -0700
Subject: [PATCH 2/9] remove putmask transpose arg, still should double-check
 new assertions

---
 pandas/core/generic.py            |  1 -
 pandas/core/internals/blocks.py   | 29 ++++++++++++++++-------------
 pandas/core/internals/managers.py |  2 ++
 3 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index b79bde9cc3cb1..3c2f6fa294e82 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -9163,7 +9163,6 @@ def _where(
                 align=align,
                 inplace=True,
                 axis=block_axis,
-                transpose=self._AXIS_REVERSED,
             )
             self._update_inplace(new_data)
 
diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index bf6ebf1abe760..9e73ad5c282d1 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -397,10 +397,6 @@ def fillna(self, value, limit=None, inplace=False, downcast=None):
                 raise ValueError("Limit must be an integer")
             if limit < 1:
                 raise ValueError("Limit must be greater than 0")
-            if self.ndim > 2:
-                raise NotImplementedError(
-                    "number of dimensions for 'fillna' is currently limited to 2"
-                )
             mask[mask.cumsum(self.ndim - 1) > limit] = False
 
         if not self._can_hold_na:
@@ -430,7 +426,9 @@ def f(m, v, i):
 
             return self.split_and_operate(mask, f, inplace)
         else:
-            blocks = self.putmask(mask, value, inplace=inplace)
+            # transpose of value is irrelevant
+            assert np.ndim(value) <= 1, value
+            blocks = self.putmask(mask.T, value, inplace=inplace)
             blocks = [
                 b.make_block(values=self._try_coerce_result(b.values)) for b in blocks
             ]
@@ -806,8 +804,9 @@ def replace(
             filtered_out = ~self.mgr_locs.isin(filter)
             mask[filtered_out.nonzero()[0]] = False
 
+        assert np.ndim(value) == 0, value
         try:
-            blocks = self.putmask(mask, value, inplace=inplace)
+            blocks = self.putmask(mask.T, value, inplace=inplace)
         except (TypeError, ValueError):
             # GH 22083, TypeError or ValueError occurred within error handling
             # causes infinite loop. Cast and retry only if not objectblock.
@@ -853,6 +852,8 @@ def setitem(self, indexer, value):
         `indexer` is a direct slice/positional indexer. `value` must
         be a compatible shape.
         """
+        transpose = self.ndim == 2
+
         # coerce None values, if appropriate
         if value is None:
             if self.is_numeric:
@@ -901,8 +902,8 @@ def setitem(self, indexer, value):
             dtype, _ = maybe_promote(arr_value.dtype)
             values = values.astype(dtype)
 
-        transf = (lambda x: x.T) if self.ndim == 2 else (lambda x: x)
-        values = transf(values)
+        if transpose:
+            values = values.T
 
         # length checking
         check_setitem_lengths(indexer, value, values)
@@ -961,10 +962,12 @@ def _is_empty_indexer(indexer):
 
         # coerce and try to infer the dtypes of the result
         values = self._try_coerce_and_cast_result(values, dtype)
-        block = self.make_block(transf(values))
+        if transpose:
+            values = values.T
+        block = self.make_block(values)
         return block
 
-    def putmask(self, mask, new, align=True, inplace=False, axis=0, transpose=False):
+    def putmask(self, mask, new, align=True, inplace=False, axis=0):
         """ putmask the data to the block; it is possible that we may create a
         new dtype of block
 
@@ -977,13 +980,12 @@ def putmask(self, mask, new, align=True, inplace=False, axis=0, transpose=False)
         align : boolean, perform alignment on other/cond, default is True
         inplace : perform inplace modification, default is False
         axis : int
-        transpose : boolean
-            Set to True if self is stored with axes reversed
 
         Returns
         -------
         a list of new blocks, the result of the putmask
         """
+        transpose = self.ndim == 2
 
         new_values = self.values if inplace else self.values.copy()
 
@@ -1630,7 +1632,8 @@ def _replace_coerce(
         if mask.any():
             if not regex:
                 self = self.coerce_to_target_dtype(value)
-                return self.putmask(mask, value, inplace=inplace)
+                assert np.ndim(value) == 0 or is_object_dtype(self), (value, self.dtype)
+                return self.putmask(mask.T, value, inplace=inplace)
             else:
                 return self._replace_single(
                     to_replace,
diff --git a/pandas/core/internals/managers.py b/pandas/core/internals/managers.py
index b3c74aaaa5701..d92a605e5d58f 100644
--- a/pandas/core/internals/managers.py
+++ b/pandas/core/internals/managers.py
@@ -584,6 +584,7 @@ def convert(self, **kwargs):
         return self.apply("convert", **kwargs)
 
     def replace(self, **kwargs):
+        assert 'value' in kwargs and np.ndim(kwargs['value']) == 0
         return self.apply("replace", **kwargs)
 
     def replace_list(self, src_list, dest_list, inplace=False, regex=False):
@@ -617,6 +618,7 @@ def comp(s, regex=False):
             # replace ALWAYS will return a list
             rb = [blk if inplace else blk.copy()]
             for i, (s, d) in enumerate(zip(src_list, dest_list)):
+                # TODO: assert/validate that `d` is always a scalar?
                 new_rb = []
                 for b in rb:
                     m = masks[i][b.mgr_locs.indexer]

From 135f4b4ff92ecbed49b7296f5fb15429b575ed6d Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Sun, 7 Jul 2019 15:04:41 -0700
Subject: [PATCH 3/9] port some test updates

---
 pandas/tests/computation/test_eval.py  |  2 +-
 pandas/tests/io/json/test_pandas.py    |  1 +
 pandas/tests/series/test_arithmetic.py | 11 ++---------
 3 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/pandas/tests/computation/test_eval.py b/pandas/tests/computation/test_eval.py
index 2fd7c8f04c8be..bc4622e9a7c55 100644
--- a/pandas/tests/computation/test_eval.py
+++ b/pandas/tests/computation/test_eval.py
@@ -411,7 +411,7 @@ def check_single_invert_op(self, lhs, cmp1, rhs):
                 )
 
     def check_compound_invert_op(self, lhs, cmp1, rhs):
-        skip_these = "in", "not in"
+        skip_these = ["in", "not in"]
         ex = "~(lhs {0} rhs)".format(cmp1)
 
         msg = (
diff --git a/pandas/tests/io/json/test_pandas.py b/pandas/tests/io/json/test_pandas.py
index a0686b53b83a4..6d532b5c69616 100644
--- a/pandas/tests/io/json/test_pandas.py
+++ b/pandas/tests/io/json/test_pandas.py
@@ -1432,6 +1432,7 @@ def test_to_jsonl(self):
         assert result == expected
         assert_frame_equal(pd.read_json(result, lines=True), df)
 
+    # TODO: there is a near-identical test for pytables; can we share?
     def test_latin_encoding(self):
         # GH 13774
         pytest.skip("encoding not implemented in .to_json(), " "xref #13774")
diff --git a/pandas/tests/series/test_arithmetic.py b/pandas/tests/series/test_arithmetic.py
index 5b57b5ba2dbae..89557445cafb4 100644
--- a/pandas/tests/series/test_arithmetic.py
+++ b/pandas/tests/series/test_arithmetic.py
@@ -24,7 +24,7 @@ class TestSeriesFlexArithmetic:
         ],
     )
     @pytest.mark.parametrize(
-        "opname", ["add", "sub", "mul", "floordiv", "truediv", "div", "pow"]
+        "opname", ["add", "sub", "mul", "floordiv", "truediv", "pow"]
     )
     def test_flex_method_equivalence(self, opname, ts):
         # check that Series.{opname} behaves like Series.__{opname}__,
@@ -34,15 +34,8 @@ def test_flex_method_equivalence(self, opname, ts):
         other = ts[1](tser)
         check_reverse = ts[2]
 
-        if opname == "div":
-            pytest.skip("div test only for Py3")
-
         op = getattr(Series, opname)
-
-        if op == "div":
-            alt = operator.truediv
-        else:
-            alt = getattr(operator, opname)
+        alt = getattr(operator, opname)
 
         result = op(series, other)
         expected = alt(series, other)

From af3409538cd97d58c54cbf996faacee2aab0c613 Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Sun, 7 Jul 2019 15:06:43 -0700
Subject: [PATCH 4/9] use transpose pattern

---
 pandas/core/generic.py          |  1 +
 pandas/core/internals/blocks.py | 19 ++++++++-----------
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 3c2f6fa294e82..b79bde9cc3cb1 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -9163,6 +9163,7 @@ def _where(
                 align=align,
                 inplace=True,
                 axis=block_axis,
+                transpose=self._AXIS_REVERSED,
             )
             self._update_inplace(new_data)
 
diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index 9e73ad5c282d1..1d436bb0010bc 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -426,9 +426,7 @@ def f(m, v, i):
 
             return self.split_and_operate(mask, f, inplace)
         else:
-            # transpose of value is irrelevant
-            assert np.ndim(value) <= 1, value
-            blocks = self.putmask(mask.T, value, inplace=inplace)
+            blocks = self.putmask(mask, value, inplace=inplace)
             blocks = [
                 b.make_block(values=self._try_coerce_result(b.values)) for b in blocks
             ]
@@ -804,9 +802,8 @@ def replace(
             filtered_out = ~self.mgr_locs.isin(filter)
             mask[filtered_out.nonzero()[0]] = False
 
-        assert np.ndim(value) == 0, value
         try:
-            blocks = self.putmask(mask.T, value, inplace=inplace)
+            blocks = self.putmask(mask, value, inplace=inplace)
         except (TypeError, ValueError):
             # GH 22083, TypeError or ValueError occurred within error handling
             # causes infinite loop. Cast and retry only if not objectblock.
@@ -903,7 +900,7 @@ def setitem(self, indexer, value):
             values = values.astype(dtype)
 
         if transpose:
-            values = values.T
+            value = values.T
 
         # length checking
         check_setitem_lengths(indexer, value, values)
@@ -963,11 +960,11 @@ def _is_empty_indexer(indexer):
         # coerce and try to infer the dtypes of the result
         values = self._try_coerce_and_cast_result(values, dtype)
         if transpose:
-            values = values.T
+            value = values.T
         block = self.make_block(values)
         return block
 
-    def putmask(self, mask, new, align=True, inplace=False, axis=0):
+    def putmask(self, mask, new, align=True, inplace=False, axis=0, transpose=False):
         """ putmask the data to the block; it is possible that we may create a
         new dtype of block
 
@@ -980,12 +977,13 @@ def putmask(self, mask, new, align=True, inplace=False, axis=0):
         align : boolean, perform alignment on other/cond, default is True
         inplace : perform inplace modification, default is False
         axis : int
+        transpose : boolean
+            Set to True if self is stored with axes reversed
 
         Returns
         -------
         a list of new blocks, the result of the putmask
         """
-        transpose = self.ndim == 2
 
         new_values = self.values if inplace else self.values.copy()
 
@@ -1632,8 +1630,7 @@ def _replace_coerce(
         if mask.any():
             if not regex:
                 self = self.coerce_to_target_dtype(value)
-                assert np.ndim(value) == 0 or is_object_dtype(self), (value, self.dtype)
-                return self.putmask(mask.T, value, inplace=inplace)
+                return self.putmask(mask, value, inplace=inplace)
             else:
                 return self._replace_single(
                     to_replace,

From 96345ffe1866e9c8074da50a20edaadce2f752c2 Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Mon, 8 Jul 2019 17:48:27 -0700
Subject: [PATCH 5/9] typo fixup

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

diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index 1d436bb0010bc..5785dbfbd6cac 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -900,7 +900,7 @@ def setitem(self, indexer, value):
             values = values.astype(dtype)
 
         if transpose:
-            value = values.T
+            values = values.T
 
         # length checking
         check_setitem_lengths(indexer, value, values)
@@ -960,7 +960,7 @@ def _is_empty_indexer(indexer):
         # coerce and try to infer the dtypes of the result
         values = self._try_coerce_and_cast_result(values, dtype)
         if transpose:
-            value = values.T
+            values = values.T
         block = self.make_block(values)
         return block
 

From 1d7d3e99aaabc2ec7a5a900881997a9b69dc7352 Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Mon, 8 Jul 2019 17:54:34 -0700
Subject: [PATCH 6/9] blackify

---
 pandas/core/internals/managers.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/internals/managers.py b/pandas/core/internals/managers.py
index d92a605e5d58f..03b505e82565b 100644
--- a/pandas/core/internals/managers.py
+++ b/pandas/core/internals/managers.py
@@ -584,7 +584,7 @@ def convert(self, **kwargs):
         return self.apply("convert", **kwargs)
 
     def replace(self, **kwargs):
-        assert 'value' in kwargs and np.ndim(kwargs['value']) == 0
+        assert "value" in kwargs and np.ndim(kwargs["value"]) == 0
         return self.apply("replace", **kwargs)
 
     def replace_list(self, src_list, dest_list, inplace=False, regex=False):

From c3dbdb824aab2e3d80b3d791bdd7797fd222cc70 Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Mon, 8 Jul 2019 18:26:47 -0700
Subject: [PATCH 7/9] Revert eager expressions import

---
 pandas/core/ops/__init__.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/pandas/core/ops/__init__.py b/pandas/core/ops/__init__.py
index b2a35fca98283..d735ab3ad2535 100644
--- a/pandas/core/ops/__init__.py
+++ b/pandas/core/ops/__init__.py
@@ -50,7 +50,6 @@
 import pandas as pd
 from pandas._typing import ArrayLike
 import pandas.core.common as com
-from pandas.core.computation import expressions
 
 from . import missing
 from .roperator import (  # noqa:F401
@@ -1255,6 +1254,7 @@ def dispatch_to_series(left, right, func, str_rep=None, axis=None):
     """
     # Note: we use iloc to access columns for compat with cases
     #       with non-unique columns.
+    import pandas.core.computation.expressions as expressions
 
     right = lib.item_from_zerodim(right)
     if lib.is_scalar(right) or np.ndim(right) == 0:
@@ -1656,6 +1656,8 @@ def na_op(x, y):
         ------
         TypeError : invalid operation
         """
+        import pandas.core.computation.expressions as expressions
+
         try:
             result = expressions.evaluate(op, str_rep, x, y, **eval_kwargs)
         except TypeError:
@@ -2156,6 +2158,8 @@ def _arith_method_FRAME(cls, op, special):
     default_axis = _get_frame_op_default_axis(op_name)
 
     def na_op(x, y):
+        import pandas.core.computation.expressions as expressions
+
         try:
             result = expressions.evaluate(op, str_rep, x, y, **eval_kwargs)
         except TypeError:

From a3b5fb3fd909b884de4440056872c96112629f1c Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Mon, 8 Jul 2019 20:11:54 -0700
Subject: [PATCH 8/9] dummy to force CI


From 275e2f81bd1367ebeb10685b88b015d1d6750f68 Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Tue, 9 Jul 2019 07:51:47 -0700
Subject: [PATCH 9/9] add value to signature

---
 pandas/core/internals/managers.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pandas/core/internals/managers.py b/pandas/core/internals/managers.py
index 03b505e82565b..cd678a235cfc1 100644
--- a/pandas/core/internals/managers.py
+++ b/pandas/core/internals/managers.py
@@ -583,9 +583,9 @@ def astype(self, dtype, **kwargs):
     def convert(self, **kwargs):
         return self.apply("convert", **kwargs)
 
-    def replace(self, **kwargs):
-        assert "value" in kwargs and np.ndim(kwargs["value"]) == 0
-        return self.apply("replace", **kwargs)
+    def replace(self, value, **kwargs):
+        assert np.ndim(value) == 0, value
+        return self.apply("replace", value=value, **kwargs)
 
     def replace_list(self, src_list, dest_list, inplace=False, regex=False):
         """ do a list replace """