From f1d7f59b6407b3e0b69e9f0d9086da5ddf04f672 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Sat, 29 Aug 2020 09:34:26 +0200
Subject: [PATCH 01/29] ENH: implement timeszones support for
 DataFrame.to_json(orient='table')

---
 doc/source/whatsnew/v1.2.0.rst                |  2 +
 pandas/io/json/_json.py                       |  4 +-
 pandas/io/json/_table_schema.py               | 40 +++++++++++++++----
 .../tests/io/json/test_json_table_schema.py   | 39 ++++++++++++++++--
 4 files changed, 73 insertions(+), 12 deletions(-)

diff --git a/doc/source/whatsnew/v1.2.0.rst b/doc/source/whatsnew/v1.2.0.rst
index f398af6e4dd5e..c6813dbbffd54 100644
--- a/doc/source/whatsnew/v1.2.0.rst
+++ b/doc/source/whatsnew/v1.2.0.rst
@@ -119,6 +119,8 @@ Other enhancements
 - :meth:`DataFrame.explode` and :meth:`Series.explode` now support exploding of sets (:issue:`35614`)
 - `Styler` now allows direct CSS class name addition to individual data cells (:issue:`36159`)
 - :meth:`Rolling.mean()` and :meth:`Rolling.sum()` use Kahan summation to calculate the mean to avoid numerical problems (:issue:`10319`, :issue:`11645`, :issue:`13254`, :issue:`32761`, :issue:`36031`)
+- :meth:`to_json` now implements timezones parsing for when orient structure is `table`.
+-
 
 .. _whatsnew_120.api_breaking.python:
 
diff --git a/pandas/io/json/_json.py b/pandas/io/json/_json.py
index c3977f89ac42f..a92038d340ff0 100644
--- a/pandas/io/json/_json.py
+++ b/pandas/io/json/_json.py
@@ -302,7 +302,9 @@ def __init__(
 
         # NotImplemented on a column MultiIndex
         if obj.ndim == 2 and isinstance(obj.columns, MultiIndex):
-            raise NotImplementedError("orient='table' is not supported for MultiIndex")
+            raise NotImplementedError(
+                "orient='table' is not supported for MultiIndex columns"
+            )
 
         # TODO: Do this timedelta properly in objToJSON.c See GH #15137
         if (
diff --git a/pandas/io/json/_table_schema.py b/pandas/io/json/_table_schema.py
index 84146a5d732e1..6aa9207fec37a 100644
--- a/pandas/io/json/_table_schema.py
+++ b/pandas/io/json/_table_schema.py
@@ -22,11 +22,11 @@
 )
 from pandas.core.dtypes.dtypes import CategoricalDtype
 
-from pandas import DataFrame
+from pandas import DataFrame, Index, MultiIndex
 import pandas.core.common as com
 
-if TYPE_CHECKING:
-    from pandas.core.indexes.multi import MultiIndex  # noqa: F401
+# if TYPE_CHECKING:
+#     from pandas.core.indexes.multi import MultiIndex  # noqa: F401
 
 loads = json.loads
 
@@ -323,9 +323,12 @@ def parse_table_schema(json, precise_float):
         for field in table["schema"]["fields"]
     }
 
-    # Cannot directly use as_type with timezone data on object; raise for now
-    if any(str(x).startswith("datetime64[ns, ") for x in dtypes.values()):
-        raise NotImplementedError('table="orient" can not yet read timezone data')
+    # tz index parsing
+    tz_info = dict()
+    for k, v in dtypes.items():
+        if str(v).startswith("datetime64[ns, "):
+            tz_info.update({k: str(v)[15:-1]})
+            dtypes[k] = "datetime64[ns]"
 
     # No ISO constructor for Timedelta as of yet, so need to raise
     if "timedelta64" in dtypes.values():
@@ -336,13 +339,34 @@ def parse_table_schema(json, precise_float):
     df = df.astype(dtypes)
 
     if "primaryKey" in table["schema"]:
-        df = df.set_index(table["schema"]["primaryKey"])
-        if len(df.index.names) == 1:
+        if len(table["schema"]["primaryKey"]) == 1:
+            df = df.set_index(table["schema"]["primaryKey"])
+            if tz_info.get(table["schema"]["primaryKey"][0], None):
+                df.index = df.index.tz_localize("UTC").tz_convert(
+                    tz_info[table["schema"]["primaryKey"][0]]
+                )
             if df.index.name == "index":
                 df.index.name = None
         else:
+            idxs = tuple(
+                idx
+                for idx in [
+                    Index(df[val])
+                    if not tz_info.get(val, None)
+                    else Index(df[val]).tz_localize("UTC").tz_convert(tz_info[val])
+                    for val in table["schema"]["primaryKey"]
+                ]
+            )
+            df.index = MultiIndex.from_tuples(
+                zip(*idxs), names=table["schema"]["primaryKey"]
+            )
+            df = df.drop(table["schema"]["primaryKey"], axis="columns")
             df.index.names = [
                 None if x.startswith("level_") else x for x in df.index.names
             ]
 
+    for col in df.columns:
+        if tz_info.get(col, None):
+            df[col] = df[col].dt.tz_localize("UTC").dt.tz_convert(tz_info[col])
+
     return df
diff --git a/pandas/tests/io/json/test_json_table_schema.py b/pandas/tests/io/json/test_json_table_schema.py
index 8f1ed193b100f..ec3c6f3a52e7c 100644
--- a/pandas/tests/io/json/test_json_table_schema.py
+++ b/pandas/tests/io/json/test_json_table_schema.py
@@ -676,6 +676,11 @@ class TestTableOrientReader:
             {"floats": [1.0, 2.0, 3.0, 4.0]},
             {"floats": [1.1, 2.2, 3.3, 4.4]},
             {"bools": [True, False, False, True]},
+            {
+                "timezones": pd.date_range(
+                    "2016-01-01", freq="d", periods=4, tz="US/Central"
+                )
+            },
         ],
     )
     @pytest.mark.skipif(sys.version_info[:3] == (3, 7, 0), reason="GH-35309")
@@ -685,18 +690,46 @@ def test_read_json_table_orient(self, index_nm, vals, recwarn):
         result = pd.read_json(out, orient="table")
         tm.assert_frame_equal(df, result)
 
-    @pytest.mark.parametrize("index_nm", [None, "idx", "index"])
+    @pytest.mark.parametrize(
+        "idx",
+        [
+            pd.Index(range(4)),
+            pd.Index(pd.date_range("2020-08-30", freq="d", periods=4,), freq=None),
+            pd.Index(
+                pd.date_range("2020-08-30", freq="d", periods=4, tz="US/Central"),
+                freq=None,
+            ),
+            pd.MultiIndex.from_product(
+                [
+                    pd.date_range("2020-08-30", freq="d", periods=2, tz="US/Central"),
+                    ["x", "y"],
+                ],
+            ),
+        ],
+    )
     @pytest.mark.parametrize(
         "vals",
         [
-            {"timedeltas": pd.timedelta_range("1H", periods=4, freq="T")},
+            {"floats": [1.1, 2.2, 3.3, 4.4]},
+            {"dates": pd.date_range("2020-08-30", freq="d", periods=4)},
             {
                 "timezones": pd.date_range(
-                    "2016-01-01", freq="d", periods=4, tz="US/Central"
+                    "2020-08-30", freq="d", periods=4, tz="Europe/London"
                 )
             },
         ],
     )
+    # @pytest.mark.skipif(sys.version_info[:3] == (3, 7, 0), reason="GH-35309")
+    def test_read_json_table_timezones_orient(self, idx, vals):
+        df = DataFrame(vals, index=idx)
+        out = df.to_json(orient="table")
+        result = pd.read_json(out, orient="table")
+        tm.assert_frame_equal(df, result)
+
+    @pytest.mark.parametrize("index_nm", [None, "idx", "index"])
+    @pytest.mark.parametrize(
+        "vals", [{"timedeltas": pd.timedelta_range("1H", periods=4, freq="T")},],
+    )
     def test_read_json_table_orient_raises(self, index_nm, vals, recwarn):
         df = DataFrame(vals, index=pd.Index(range(4), name=index_nm))
         out = df.to_json(orient="table")

From eeb6201cde99c7eac2d60a77a9044830caaa326e Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Sat, 29 Aug 2020 09:46:50 +0200
Subject: [PATCH 02/29] pep8

---
 pandas/tests/io/json/test_json_table_schema.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/io/json/test_json_table_schema.py b/pandas/tests/io/json/test_json_table_schema.py
index ec3c6f3a52e7c..b6dbc5705e2c2 100644
--- a/pandas/tests/io/json/test_json_table_schema.py
+++ b/pandas/tests/io/json/test_json_table_schema.py
@@ -728,7 +728,7 @@ def test_read_json_table_timezones_orient(self, idx, vals):
 
     @pytest.mark.parametrize("index_nm", [None, "idx", "index"])
     @pytest.mark.parametrize(
-        "vals", [{"timedeltas": pd.timedelta_range("1H", periods=4, freq="T")},],
+        "vals", [{"timedeltas": pd.timedelta_range("1H", periods=4, freq="T")}],
     )
     def test_read_json_table_orient_raises(self, index_nm, vals, recwarn):
         df = DataFrame(vals, index=pd.Index(range(4), name=index_nm))

From 95b9501a828dd62ac6acc65afaf564a03593429a Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Sat, 29 Aug 2020 10:00:08 +0200
Subject: [PATCH 03/29] minor cleanup

---
 doc/source/whatsnew/v1.2.0.rst                |  1 +
 pandas/io/json/_table_schema.py               |  5 +----
 .../tests/io/json/test_json_table_schema.py   | 20 +++++++++----------
 3 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/doc/source/whatsnew/v1.2.0.rst b/doc/source/whatsnew/v1.2.0.rst
index c6813dbbffd54..c96c95c469849 100644
--- a/doc/source/whatsnew/v1.2.0.rst
+++ b/doc/source/whatsnew/v1.2.0.rst
@@ -120,6 +120,7 @@ Other enhancements
 - `Styler` now allows direct CSS class name addition to individual data cells (:issue:`36159`)
 - :meth:`Rolling.mean()` and :meth:`Rolling.sum()` use Kahan summation to calculate the mean to avoid numerical problems (:issue:`10319`, :issue:`11645`, :issue:`13254`, :issue:`32761`, :issue:`36031`)
 - :meth:`to_json` now implements timezones parsing for when orient structure is `table`.
+- :meth:`read_json` now implements timezones parsing for when orient structure is `table`.
 -
 
 .. _whatsnew_120.api_breaking.python:
diff --git a/pandas/io/json/_table_schema.py b/pandas/io/json/_table_schema.py
index 6aa9207fec37a..72b884197d696 100644
--- a/pandas/io/json/_table_schema.py
+++ b/pandas/io/json/_table_schema.py
@@ -3,7 +3,7 @@
 
 https://specs.frictionlessdata.io/json-table-schema/
 """
-from typing import TYPE_CHECKING, Any, Dict, Optional, cast
+from typing import Any, Dict, Optional, cast
 import warnings
 
 import pandas._libs.json as json
@@ -25,9 +25,6 @@
 from pandas import DataFrame, Index, MultiIndex
 import pandas.core.common as com
 
-# if TYPE_CHECKING:
-#     from pandas.core.indexes.multi import MultiIndex  # noqa: F401
-
 loads = json.loads
 
 
diff --git a/pandas/tests/io/json/test_json_table_schema.py b/pandas/tests/io/json/test_json_table_schema.py
index b6dbc5705e2c2..31bce5c07f56b 100644
--- a/pandas/tests/io/json/test_json_table_schema.py
+++ b/pandas/tests/io/json/test_json_table_schema.py
@@ -690,6 +690,16 @@ def test_read_json_table_orient(self, index_nm, vals, recwarn):
         result = pd.read_json(out, orient="table")
         tm.assert_frame_equal(df, result)
 
+    @pytest.mark.parametrize("index_nm", [None, "idx", "index"])
+    @pytest.mark.parametrize(
+        "vals", [{"timedeltas": pd.timedelta_range("1H", periods=4, freq="T")}],
+    )
+    def test_read_json_table_orient_raises(self, index_nm, vals, recwarn):
+        df = DataFrame(vals, index=pd.Index(range(4), name=index_nm))
+        out = df.to_json(orient="table")
+        with pytest.raises(NotImplementedError, match="can not yet read "):
+            pd.read_json(out, orient="table")
+
     @pytest.mark.parametrize(
         "idx",
         [
@@ -726,16 +736,6 @@ def test_read_json_table_timezones_orient(self, idx, vals):
         result = pd.read_json(out, orient="table")
         tm.assert_frame_equal(df, result)
 
-    @pytest.mark.parametrize("index_nm", [None, "idx", "index"])
-    @pytest.mark.parametrize(
-        "vals", [{"timedeltas": pd.timedelta_range("1H", periods=4, freq="T")}],
-    )
-    def test_read_json_table_orient_raises(self, index_nm, vals, recwarn):
-        df = DataFrame(vals, index=pd.Index(range(4), name=index_nm))
-        out = df.to_json(orient="table")
-        with pytest.raises(NotImplementedError, match="can not yet read "):
-            pd.read_json(out, orient="table")
-
     def test_comprehensive(self):
         df = DataFrame(
             {

From c057358f88c3cb7d1106233ce9225d489d1c4d83 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Sat, 29 Aug 2020 10:12:57 +0200
Subject: [PATCH 04/29] linting and type cleanup

---
 pandas/io/json/_table_schema.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pandas/io/json/_table_schema.py b/pandas/io/json/_table_schema.py
index 72b884197d696..c8cf7e22aeb46 100644
--- a/pandas/io/json/_table_schema.py
+++ b/pandas/io/json/_table_schema.py
@@ -22,7 +22,7 @@
 )
 from pandas.core.dtypes.dtypes import CategoricalDtype
 
-from pandas import DataFrame, Index, MultiIndex
+from pandas import DataFrame, Index, MultiIndex, DatetimeIndex
 import pandas.core.common as com
 
 loads = json.loads
@@ -350,7 +350,9 @@ def parse_table_schema(json, precise_float):
                 for idx in [
                     Index(df[val])
                     if not tz_info.get(val, None)
-                    else Index(df[val]).tz_localize("UTC").tz_convert(tz_info[val])
+                    else DatetimeIndex(df[val])
+                    .tz_localize("UTC")
+                    .tz_convert(tz_info[val])
                     for val in table["schema"]["primaryKey"]
                 ]
             )

From 70b1448f47fdeec6e702b7e3d7418cd84ce8cd84 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Sat, 29 Aug 2020 10:46:18 +0200
Subject: [PATCH 05/29] isort

---
 pandas/io/json/_table_schema.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/io/json/_table_schema.py b/pandas/io/json/_table_schema.py
index c8cf7e22aeb46..8589bfc5dd821 100644
--- a/pandas/io/json/_table_schema.py
+++ b/pandas/io/json/_table_schema.py
@@ -22,7 +22,7 @@
 )
 from pandas.core.dtypes.dtypes import CategoricalDtype
 
-from pandas import DataFrame, Index, MultiIndex, DatetimeIndex
+from pandas import DataFrame, DatetimeIndex, Index, MultiIndex
 import pandas.core.common as com
 
 loads = json.loads

From e762ce0d877be6a6de0ea8bec9c45c03d6127903 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Sat, 29 Aug 2020 11:24:09 +0200
Subject: [PATCH 06/29] static type ignore

---
 pandas/io/json/_table_schema.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/pandas/io/json/_table_schema.py b/pandas/io/json/_table_schema.py
index 8589bfc5dd821..5584b32d2ea14 100644
--- a/pandas/io/json/_table_schema.py
+++ b/pandas/io/json/_table_schema.py
@@ -350,8 +350,7 @@ def parse_table_schema(json, precise_float):
                 for idx in [
                     Index(df[val])
                     if not tz_info.get(val, None)
-                    else DatetimeIndex(df[val])
-                    .tz_localize("UTC")
+                    else DatetimeIndex(df[val], tz="UTC")  # type: ignore
                     .tz_convert(tz_info[val])
                     for val in table["schema"]["primaryKey"]
                 ]

From 61ca6a88ad01ec673a1216eeabb2fcd5407cf8da Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Sat, 29 Aug 2020 12:16:47 +0200
Subject: [PATCH 07/29] black and mypy fix to work together

---
 pandas/io/json/_table_schema.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pandas/io/json/_table_schema.py b/pandas/io/json/_table_schema.py
index 5584b32d2ea14..fb409baa3cce2 100644
--- a/pandas/io/json/_table_schema.py
+++ b/pandas/io/json/_table_schema.py
@@ -350,8 +350,9 @@ def parse_table_schema(json, precise_float):
                 for idx in [
                     Index(df[val])
                     if not tz_info.get(val, None)
-                    else DatetimeIndex(df[val], tz="UTC")  # type: ignore
-                    .tz_convert(tz_info[val])
+                    else DatetimeIndex(df[val], tz="UTC").tz_convert(  # type: ignore
+                        tz_info[val]
+                    )
                     for val in table["schema"]["primaryKey"]
                 ]
             )

From f9d071a7a428630c2c0d48a5a070ca851d45031e Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Mon, 31 Aug 2020 23:58:15 +0200
Subject: [PATCH 08/29] re-write so conversion occurs in astype() as opposed to
 parse_json()

---
 pandas/core/arrays/datetimes.py | 13 ++++++++++++-
 pandas/io/json/_table_schema.py | 34 ++-------------------------------
 2 files changed, 14 insertions(+), 33 deletions(-)

diff --git a/pandas/core/arrays/datetimes.py b/pandas/core/arrays/datetimes.py
index 2073f110d536f..6c33e06b3b262 100644
--- a/pandas/core/arrays/datetimes.py
+++ b/pandas/core/arrays/datetimes.py
@@ -1949,7 +1949,18 @@ def sequence_to_dt64ns(
             data, inferred_tz = objects_to_datetime64ns(
                 data, dayfirst=dayfirst, yearfirst=yearfirst
             )
-            tz = _maybe_infer_tz(tz, inferred_tz)
+            try:
+                tz = _maybe_infer_tz(tz, inferred_tz)
+            except TypeError as e:
+                #  TODO: make generic conversion instead of only from UTC
+                if inferred_tz.zone == "UTC":
+                    data = tzconversion.tz_convert_from_utc(
+                        data.view("i8"), tz
+                    )
+                    data = data.view(DT64NS_DTYPE)
+                else:
+                    raise e
+
         data_dtype = data.dtype
 
     # `data` may have originally been a Categorical[datetime64[ns, tz]],
diff --git a/pandas/io/json/_table_schema.py b/pandas/io/json/_table_schema.py
index fb409baa3cce2..40941ffd09d1c 100644
--- a/pandas/io/json/_table_schema.py
+++ b/pandas/io/json/_table_schema.py
@@ -320,13 +320,6 @@ def parse_table_schema(json, precise_float):
         for field in table["schema"]["fields"]
     }
 
-    # tz index parsing
-    tz_info = dict()
-    for k, v in dtypes.items():
-        if str(v).startswith("datetime64[ns, "):
-            tz_info.update({k: str(v)[15:-1]})
-            dtypes[k] = "datetime64[ns]"
-
     # No ISO constructor for Timedelta as of yet, so need to raise
     if "timedelta64" in dtypes.values():
         raise NotImplementedError(
@@ -336,36 +329,13 @@ def parse_table_schema(json, precise_float):
     df = df.astype(dtypes)
 
     if "primaryKey" in table["schema"]:
-        if len(table["schema"]["primaryKey"]) == 1:
-            df = df.set_index(table["schema"]["primaryKey"])
-            if tz_info.get(table["schema"]["primaryKey"][0], None):
-                df.index = df.index.tz_localize("UTC").tz_convert(
-                    tz_info[table["schema"]["primaryKey"][0]]
-                )
+        df = df.set_index(table["schema"]["primaryKey"])
+        if len(df.index.names) == 1:
             if df.index.name == "index":
                 df.index.name = None
         else:
-            idxs = tuple(
-                idx
-                for idx in [
-                    Index(df[val])
-                    if not tz_info.get(val, None)
-                    else DatetimeIndex(df[val], tz="UTC").tz_convert(  # type: ignore
-                        tz_info[val]
-                    )
-                    for val in table["schema"]["primaryKey"]
-                ]
-            )
-            df.index = MultiIndex.from_tuples(
-                zip(*idxs), names=table["schema"]["primaryKey"]
-            )
-            df = df.drop(table["schema"]["primaryKey"], axis="columns")
             df.index.names = [
                 None if x.startswith("level_") else x for x in df.index.names
             ]
 
-    for col in df.columns:
-        if tz_info.get(col, None):
-            df[col] = df[col].dt.tz_localize("UTC").dt.tz_convert(tz_info[col])
-
     return df

From 79bd2eb0d64e87b962a8dc9b0d139746d21c7c50 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Tue, 1 Sep 2020 00:08:45 +0200
Subject: [PATCH 09/29] removed unused imports

---
 pandas/io/json/_table_schema.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/io/json/_table_schema.py b/pandas/io/json/_table_schema.py
index 40941ffd09d1c..3039e1bc65022 100644
--- a/pandas/io/json/_table_schema.py
+++ b/pandas/io/json/_table_schema.py
@@ -22,7 +22,7 @@
 )
 from pandas.core.dtypes.dtypes import CategoricalDtype
 
-from pandas import DataFrame, DatetimeIndex, Index, MultiIndex
+from pandas import DataFrame
 import pandas.core.common as com
 
 loads = json.loads

From f9f413f117cf5d89231eb35d3719d6bc09fa2b38 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Tue, 1 Sep 2020 00:16:53 +0200
Subject: [PATCH 10/29] black fix

---
 pandas/core/arrays/datetimes.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/pandas/core/arrays/datetimes.py b/pandas/core/arrays/datetimes.py
index 6c33e06b3b262..c144de0ec19f1 100644
--- a/pandas/core/arrays/datetimes.py
+++ b/pandas/core/arrays/datetimes.py
@@ -1954,9 +1954,7 @@ def sequence_to_dt64ns(
             except TypeError as e:
                 #  TODO: make generic conversion instead of only from UTC
                 if inferred_tz.zone == "UTC":
-                    data = tzconversion.tz_convert_from_utc(
-                        data.view("i8"), tz
-                    )
+                    data = tzconversion.tz_convert_from_utc(data.view("i8"), tz)
                     data = data.view(DT64NS_DTYPE)
                 else:
                     raise e

From ce51e30d63fba6e234a254d3808e5337ad8ef08a Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Tue, 1 Sep 2020 06:48:42 +0200
Subject: [PATCH 11/29] typing

---
 pandas/io/json/_table_schema.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pandas/io/json/_table_schema.py b/pandas/io/json/_table_schema.py
index 3039e1bc65022..f55f2fdcc6107 100644
--- a/pandas/io/json/_table_schema.py
+++ b/pandas/io/json/_table_schema.py
@@ -3,7 +3,7 @@
 
 https://specs.frictionlessdata.io/json-table-schema/
 """
-from typing import Any, Dict, Optional, cast
+from typing import TYPE_CHECKING, Any, Dict, Optional, cast
 import warnings
 
 import pandas._libs.json as json
@@ -25,6 +25,9 @@
 from pandas import DataFrame
 import pandas.core.common as com
 
+if TYPE_CHECKING:
+    from pandas.core.indexes.multi import MultiIndex  # noqa: F401
+
 loads = json.loads
 
 

From 37cad4f82c1fc9a6a7e891bc2773994bed98891d Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Tue, 1 Sep 2020 21:07:33 +0200
Subject: [PATCH 12/29] astype conversion for objects of one tz to another tz

---
 doc/source/whatsnew/v1.2.0.rst                |  1 +
 pandas/core/arrays/datetimes.py               |  9 +++-----
 .../tests/io/json/test_json_table_schema.py   |  1 -
 pandas/tests/tslibs/test_timezones.py         | 22 ++++++++++++++++++-
 4 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/doc/source/whatsnew/v1.2.0.rst b/doc/source/whatsnew/v1.2.0.rst
index c96c95c469849..4e888c6d16763 100644
--- a/doc/source/whatsnew/v1.2.0.rst
+++ b/doc/source/whatsnew/v1.2.0.rst
@@ -121,6 +121,7 @@ Other enhancements
 - :meth:`Rolling.mean()` and :meth:`Rolling.sum()` use Kahan summation to calculate the mean to avoid numerical problems (:issue:`10319`, :issue:`11645`, :issue:`13254`, :issue:`32761`, :issue:`36031`)
 - :meth:`to_json` now implements timezones parsing for when orient structure is `table`.
 - :meth:`read_json` now implements timezones parsing for when orient structure is `table`.
+- :meth:`astype` now attempts to convert to `datetime64[ns, tz]` directly from `object` with inferred timezone from string (:issue:`35973`).
 -
 
 .. _whatsnew_120.api_breaking.python:
diff --git a/pandas/core/arrays/datetimes.py b/pandas/core/arrays/datetimes.py
index c144de0ec19f1..3012d0435d6a8 100644
--- a/pandas/core/arrays/datetimes.py
+++ b/pandas/core/arrays/datetimes.py
@@ -1952,12 +1952,9 @@ def sequence_to_dt64ns(
             try:
                 tz = _maybe_infer_tz(tz, inferred_tz)
             except TypeError as e:
-                #  TODO: make generic conversion instead of only from UTC
-                if inferred_tz.zone == "UTC":
-                    data = tzconversion.tz_convert_from_utc(data.view("i8"), tz)
-                    data = data.view(DT64NS_DTYPE)
-                else:
-                    raise e
+                #  two timezones: convert to intended from base UTC repr
+                data = tzconversion.tz_convert_from_utc(data.view("i8"), tz)
+                data = data.view(DT64NS_DTYPE)
 
         data_dtype = data.dtype
 
diff --git a/pandas/tests/io/json/test_json_table_schema.py b/pandas/tests/io/json/test_json_table_schema.py
index 31bce5c07f56b..8e163c8cd0339 100644
--- a/pandas/tests/io/json/test_json_table_schema.py
+++ b/pandas/tests/io/json/test_json_table_schema.py
@@ -729,7 +729,6 @@ def test_read_json_table_orient_raises(self, index_nm, vals, recwarn):
             },
         ],
     )
-    # @pytest.mark.skipif(sys.version_info[:3] == (3, 7, 0), reason="GH-35309")
     def test_read_json_table_timezones_orient(self, idx, vals):
         df = DataFrame(vals, index=idx)
         out = df.to_json(orient="table")
diff --git a/pandas/tests/tslibs/test_timezones.py b/pandas/tests/tslibs/test_timezones.py
index 81b41f567976d..65bd27ba1ddd8 100644
--- a/pandas/tests/tslibs/test_timezones.py
+++ b/pandas/tests/tslibs/test_timezones.py
@@ -5,8 +5,9 @@
 import pytz
 
 from pandas._libs.tslibs import conversion, timezones
+import pandas._testing as tm
 
-from pandas import Timestamp
+from pandas import Timestamp, DataFrame, date_range
 
 
 @pytest.mark.parametrize("tz_name", list(pytz.common_timezones))
@@ -118,3 +119,22 @@ def test_maybe_get_tz_invalid_types():
     msg = "<class 'pandas._libs.tslibs.timestamps.Timestamp'>"
     with pytest.raises(TypeError, match=msg):
         timezones.maybe_get_tz(Timestamp.now("UTC"))
+
+
+def test_astype_tz_conversion_roundtrip():
+    vals = {
+        "timezones": date_range("2020-08-30", freq="d", periods=2, tz="Europe/London")
+    }
+    df = DataFrame(vals)
+
+    # test UTC inferred object to specified tz
+    result = df.astype({"timezones": "datetime64[ns, UTC]"})  # convert tz to UTC
+    result = df.astype({"timezones": "object"})  # convert to string
+    result = df.astype({"timezones": "datetime64[ns, Europe/London]"})
+    tm.assert_frame_equal(df, result)
+
+    # test non-UTC inferred_tz to specified tz
+    result = df.astype({"timezones": "datetime64[ns, Europe/Berlin]"})
+    result = df.astype({"timezones": "object"})  # convert to string
+    result = df.astype({"timezones": "datetime64[ns, Europe/London]"})
+    tm.assert_frame_equal(df, result)

From 39740d8b0baa5ee835950977403226c7a923db3f Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Tue, 1 Sep 2020 21:37:31 +0200
Subject: [PATCH 13/29] linting isort

---
 pandas/core/arrays/datetimes.py       | 2 +-
 pandas/tests/tslibs/test_timezones.py | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/pandas/core/arrays/datetimes.py b/pandas/core/arrays/datetimes.py
index 3012d0435d6a8..7a5a6dbb93645 100644
--- a/pandas/core/arrays/datetimes.py
+++ b/pandas/core/arrays/datetimes.py
@@ -1951,7 +1951,7 @@ def sequence_to_dt64ns(
             )
             try:
                 tz = _maybe_infer_tz(tz, inferred_tz)
-            except TypeError as e:
+            except TypeError:
                 #  two timezones: convert to intended from base UTC repr
                 data = tzconversion.tz_convert_from_utc(data.view("i8"), tz)
                 data = data.view(DT64NS_DTYPE)
diff --git a/pandas/tests/tslibs/test_timezones.py b/pandas/tests/tslibs/test_timezones.py
index 65bd27ba1ddd8..14c60ca8275c2 100644
--- a/pandas/tests/tslibs/test_timezones.py
+++ b/pandas/tests/tslibs/test_timezones.py
@@ -5,9 +5,9 @@
 import pytz
 
 from pandas._libs.tslibs import conversion, timezones
-import pandas._testing as tm
 
-from pandas import Timestamp, DataFrame, date_range
+from pandas import DataFrame, Timestamp, date_range
+import pandas._testing as tm
 
 
 @pytest.mark.parametrize("tz_name", list(pytz.common_timezones))

From d1a9cd3d3ece6f3c6a8a1e82476035a7ff0d04b0 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Wed, 2 Sep 2020 21:48:06 +0200
Subject: [PATCH 14/29] move tests

---
 pandas/tests/indexes/period/test_astype.py | 22 ++++++++++++++++++++++
 pandas/tests/tslibs/test_timezones.py      | 22 +---------------------
 2 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/pandas/tests/indexes/period/test_astype.py b/pandas/tests/indexes/period/test_astype.py
index fa1617bdfaa52..abc6f9bb8ed87 100644
--- a/pandas/tests/indexes/period/test_astype.py
+++ b/pandas/tests/indexes/period/test_astype.py
@@ -3,6 +3,7 @@
 
 from pandas import (
     CategoricalIndex,
+    DataFrame,
     DatetimeIndex,
     Index,
     Int64Index,
@@ -11,6 +12,7 @@
     PeriodIndex,
     Timedelta,
     UInt64Index,
+    date_range,
     period_range,
 )
 import pandas._testing as tm
@@ -164,3 +166,23 @@ def test_period_astype_to_timestamp(self):
         res = pi.astype("datetime64[ns, US/Eastern]", how="end")
         tm.assert_index_equal(res, exp)
         assert res.freq == exp.freq
+
+    def test_astype_tz_conversion_roundtrip(self):
+        vals = {
+            "timezones": date_range(
+                "2020-08-30", freq="d", periods=2, tz="Europe/London"
+            )
+        }
+        df = DataFrame(vals)
+
+        # test UTC inferred object to specified tz
+        result = df.astype({"timezones": "datetime64[ns, UTC]"})  # convert tz to UTC
+        result = df.astype({"timezones": "object"})  # convert to string
+        result = df.astype({"timezones": "datetime64[ns, Europe/London]"})
+        tm.assert_frame_equal(df, result)
+
+        # test non-UTC inferred_tz to specified tz
+        result = df.astype({"timezones": "datetime64[ns, Europe/Berlin]"})
+        result = df.astype({"timezones": "object"})  # convert to string
+        result = df.astype({"timezones": "datetime64[ns, Europe/London]"})
+        tm.assert_frame_equal(df, result)
diff --git a/pandas/tests/tslibs/test_timezones.py b/pandas/tests/tslibs/test_timezones.py
index 14c60ca8275c2..81b41f567976d 100644
--- a/pandas/tests/tslibs/test_timezones.py
+++ b/pandas/tests/tslibs/test_timezones.py
@@ -6,8 +6,7 @@
 
 from pandas._libs.tslibs import conversion, timezones
 
-from pandas import DataFrame, Timestamp, date_range
-import pandas._testing as tm
+from pandas import Timestamp
 
 
 @pytest.mark.parametrize("tz_name", list(pytz.common_timezones))
@@ -119,22 +118,3 @@ def test_maybe_get_tz_invalid_types():
     msg = "<class 'pandas._libs.tslibs.timestamps.Timestamp'>"
     with pytest.raises(TypeError, match=msg):
         timezones.maybe_get_tz(Timestamp.now("UTC"))
-
-
-def test_astype_tz_conversion_roundtrip():
-    vals = {
-        "timezones": date_range("2020-08-30", freq="d", periods=2, tz="Europe/London")
-    }
-    df = DataFrame(vals)
-
-    # test UTC inferred object to specified tz
-    result = df.astype({"timezones": "datetime64[ns, UTC]"})  # convert tz to UTC
-    result = df.astype({"timezones": "object"})  # convert to string
-    result = df.astype({"timezones": "datetime64[ns, Europe/London]"})
-    tm.assert_frame_equal(df, result)
-
-    # test non-UTC inferred_tz to specified tz
-    result = df.astype({"timezones": "datetime64[ns, Europe/Berlin]"})
-    result = df.astype({"timezones": "object"})  # convert to string
-    result = df.astype({"timezones": "datetime64[ns, Europe/London]"})
-    tm.assert_frame_equal(df, result)

From bb8f7b96f58c9e7322ee7b36c18eb720ff3580b2 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Wed, 2 Sep 2020 22:15:30 +0200
Subject: [PATCH 15/29] move tests

---
 pandas/tests/indexes/period/test_astype.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas/tests/indexes/period/test_astype.py b/pandas/tests/indexes/period/test_astype.py
index abc6f9bb8ed87..803541f5d3899 100644
--- a/pandas/tests/indexes/period/test_astype.py
+++ b/pandas/tests/indexes/period/test_astype.py
@@ -168,6 +168,7 @@ def test_period_astype_to_timestamp(self):
         assert res.freq == exp.freq
 
     def test_astype_tz_conversion_roundtrip(self):
+        # GH 35973
         vals = {
             "timezones": date_range(
                 "2020-08-30", freq="d", periods=2, tz="Europe/London"

From b55ccedb6812893afcf6728f76e23572f8d10c6d Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Sun, 13 Sep 2020 07:53:09 +0200
Subject: [PATCH 16/29] seg fault failure fix?

---
 pandas/tests/io/json/test_json_table_schema.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/io/json/test_json_table_schema.py b/pandas/tests/io/json/test_json_table_schema.py
index 8e163c8cd0339..db4dca7de0fd4 100644
--- a/pandas/tests/io/json/test_json_table_schema.py
+++ b/pandas/tests/io/json/test_json_table_schema.py
@@ -729,7 +729,8 @@ def test_read_json_table_orient_raises(self, index_nm, vals, recwarn):
             },
         ],
     )
-    def test_read_json_table_timezones_orient(self, idx, vals):
+    @pytest.mark.skipif(sys.version_info[:3] == (3, 7, 0), reason="GH-35309")
+    def test_read_json_table_timezones_orient(self, idx, vals, recwarn):
         df = DataFrame(vals, index=idx)
         out = df.to_json(orient="table")
         result = pd.read_json(out, orient="table")

From 5bc4b2ce1e8add6cf6df60d4a9c5bb0656a0f820 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Wed, 16 Sep 2020 07:40:26 +0200
Subject: [PATCH 17/29] remove raise condition

---
 pandas/core/arrays/datetimes.py | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/pandas/core/arrays/datetimes.py b/pandas/core/arrays/datetimes.py
index 7a5a6dbb93645..65c80e5d385d8 100644
--- a/pandas/core/arrays/datetimes.py
+++ b/pandas/core/arrays/datetimes.py
@@ -1949,12 +1949,19 @@ def sequence_to_dt64ns(
             data, inferred_tz = objects_to_datetime64ns(
                 data, dayfirst=dayfirst, yearfirst=yearfirst
             )
-            try:
-                tz = _maybe_infer_tz(tz, inferred_tz)
-            except TypeError:
+            if tz and inferred_tz:
                 #  two timezones: convert to intended from base UTC repr
                 data = tzconversion.tz_convert_from_utc(data.view("i8"), tz)
                 data = data.view(DT64NS_DTYPE)
+            elif inferred_tz:
+                tz = inferred_tz
+
+            # try:
+            #     tz = _maybe_infer_tz(tz, inferred_tz)
+            # except TypeError:
+            #     #  two timezones: convert to intended from base UTC repr
+            #     data = tzconversion.tz_convert_from_utc(data.view("i8"), tz)
+            #     data = data.view(DT64NS_DTYPE)
 
         data_dtype = data.dtype
 

From a6c7ec65d9eac2f4505582b598bb58d3ac5babb4 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Wed, 16 Sep 2020 09:03:11 +0200
Subject: [PATCH 18/29] eliminate try-except and move tests

---
 pandas/core/arrays/datetimes.py            |  7 ------
 pandas/tests/frame/methods/test_astype.py  | 26 ++++++++++++++++++++++
 pandas/tests/indexes/period/test_astype.py | 20 -----------------
 3 files changed, 26 insertions(+), 27 deletions(-)

diff --git a/pandas/core/arrays/datetimes.py b/pandas/core/arrays/datetimes.py
index 65c80e5d385d8..3f68c8cd331fb 100644
--- a/pandas/core/arrays/datetimes.py
+++ b/pandas/core/arrays/datetimes.py
@@ -1956,13 +1956,6 @@ def sequence_to_dt64ns(
             elif inferred_tz:
                 tz = inferred_tz
 
-            # try:
-            #     tz = _maybe_infer_tz(tz, inferred_tz)
-            # except TypeError:
-            #     #  two timezones: convert to intended from base UTC repr
-            #     data = tzconversion.tz_convert_from_utc(data.view("i8"), tz)
-            #     data = data.view(DT64NS_DTYPE)
-
         data_dtype = data.dtype
 
     # `data` may have originally been a Categorical[datetime64[ns, tz]],
diff --git a/pandas/tests/frame/methods/test_astype.py b/pandas/tests/frame/methods/test_astype.py
index d3f256259b15f..8d869d02f5611 100644
--- a/pandas/tests/frame/methods/test_astype.py
+++ b/pandas/tests/frame/methods/test_astype.py
@@ -587,3 +587,29 @@ def test_astype_ignores_errors_for_extension_dtypes(self, df, errors):
             msg = "(Cannot cast)|(could not convert)"
             with pytest.raises((ValueError, TypeError), match=msg):
                 df.astype(float, errors=errors)
+
+    def test_astype_tz_conversion(self):
+        # GH 35973
+        val = {"tz": date_range("2020-08-30", freq="d", periods=2, tz="Europe/London")}
+        df, df2 = DataFrame(val), DataFrame(val)
+        df2['tz'] = df2['tz'].dt.tz_convert('Europe/Berlin')
+
+        tm.assert_frame_equal(df.astype({"tz": "datetime64[ns, Europe/Berlin]"}), df2)
+
+    @pytest.mark.parametrize("tz", ["UTC", "Europe/Berlin"])
+    def test_astype_tz_object_conversion(self, tz):
+        # GH 35973
+        # Test UTC, non-UTC inferred object to an original and specified tz.
+        vals = {
+            "timezones": date_range(
+                "2020-08-30", freq="d", periods=2, tz="Europe/London"
+            )
+        }
+        base = DataFrame(vals)
+
+        # convert base to input test param and then to object dtype
+        result = base.astype({"timezones": "datetime64[ns, {}]".format(tz)})
+        result = result.astype({"timezones": "object"})
+        # test conversion of object dtype to a specified tz, different to inferred.
+        result = result.astype({"timezones": "datetime64[ns, Europe/London]"})
+        tm.assert_frame_equal(base, result)
diff --git a/pandas/tests/indexes/period/test_astype.py b/pandas/tests/indexes/period/test_astype.py
index 803541f5d3899..5f67b4f7fcaca 100644
--- a/pandas/tests/indexes/period/test_astype.py
+++ b/pandas/tests/indexes/period/test_astype.py
@@ -167,23 +167,3 @@ def test_period_astype_to_timestamp(self):
         tm.assert_index_equal(res, exp)
         assert res.freq == exp.freq
 
-    def test_astype_tz_conversion_roundtrip(self):
-        # GH 35973
-        vals = {
-            "timezones": date_range(
-                "2020-08-30", freq="d", periods=2, tz="Europe/London"
-            )
-        }
-        df = DataFrame(vals)
-
-        # test UTC inferred object to specified tz
-        result = df.astype({"timezones": "datetime64[ns, UTC]"})  # convert tz to UTC
-        result = df.astype({"timezones": "object"})  # convert to string
-        result = df.astype({"timezones": "datetime64[ns, Europe/London]"})
-        tm.assert_frame_equal(df, result)
-
-        # test non-UTC inferred_tz to specified tz
-        result = df.astype({"timezones": "datetime64[ns, Europe/Berlin]"})
-        result = df.astype({"timezones": "object"})  # convert to string
-        result = df.astype({"timezones": "datetime64[ns, Europe/London]"})
-        tm.assert_frame_equal(df, result)

From a192c6686d8afae2979f77d824fd3c444634bd46 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Wed, 16 Sep 2020 09:04:59 +0200
Subject: [PATCH 19/29] black fix

---
 pandas/tests/frame/methods/test_astype.py  | 7 ++++---
 pandas/tests/indexes/period/test_astype.py | 1 -
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/pandas/tests/frame/methods/test_astype.py b/pandas/tests/frame/methods/test_astype.py
index 8d869d02f5611..7363a60598b05 100644
--- a/pandas/tests/frame/methods/test_astype.py
+++ b/pandas/tests/frame/methods/test_astype.py
@@ -592,7 +592,7 @@ def test_astype_tz_conversion(self):
         # GH 35973
         val = {"tz": date_range("2020-08-30", freq="d", periods=2, tz="Europe/London")}
         df, df2 = DataFrame(val), DataFrame(val)
-        df2['tz'] = df2['tz'].dt.tz_convert('Europe/Berlin')
+        df2["tz"] = df2["tz"].dt.tz_convert("Europe/Berlin")
 
         tm.assert_frame_equal(df.astype({"tz": "datetime64[ns, Europe/Berlin]"}), df2)
 
@@ -608,8 +608,9 @@ def test_astype_tz_object_conversion(self, tz):
         base = DataFrame(vals)
 
         # convert base to input test param and then to object dtype
-        result = base.astype({"timezones": "datetime64[ns, {}]".format(tz)})
-        result = result.astype({"timezones": "object"})
+        result = base.astype({"timezones": "datetime64[ns, {}]".format(tz)}).astype(
+            {"timezones": "object"}
+        )
         # test conversion of object dtype to a specified tz, different to inferred.
         result = result.astype({"timezones": "datetime64[ns, Europe/London]"})
         tm.assert_frame_equal(base, result)
diff --git a/pandas/tests/indexes/period/test_astype.py b/pandas/tests/indexes/period/test_astype.py
index 5f67b4f7fcaca..20c4fa2cbf6c9 100644
--- a/pandas/tests/indexes/period/test_astype.py
+++ b/pandas/tests/indexes/period/test_astype.py
@@ -166,4 +166,3 @@ def test_period_astype_to_timestamp(self):
         res = pi.astype("datetime64[ns, US/Eastern]", how="end")
         tm.assert_index_equal(res, exp)
         assert res.freq == exp.freq
-

From 6d989452a574656ec6ce6b95e2ee2b06f3664e65 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Wed, 16 Sep 2020 09:12:41 +0200
Subject: [PATCH 20/29] issues stamp

---
 pandas/tests/io/json/test_json_table_schema.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/io/json/test_json_table_schema.py b/pandas/tests/io/json/test_json_table_schema.py
index db4dca7de0fd4..d94b48d4b4028 100644
--- a/pandas/tests/io/json/test_json_table_schema.py
+++ b/pandas/tests/io/json/test_json_table_schema.py
@@ -679,7 +679,7 @@ class TestTableOrientReader:
             {
                 "timezones": pd.date_range(
                     "2016-01-01", freq="d", periods=4, tz="US/Central"
-                )
+                )  # added in # GH 35973
             },
         ],
     )
@@ -731,6 +731,7 @@ def test_read_json_table_orient_raises(self, index_nm, vals, recwarn):
     )
     @pytest.mark.skipif(sys.version_info[:3] == (3, 7, 0), reason="GH-35309")
     def test_read_json_table_timezones_orient(self, idx, vals, recwarn):
+        # GH 35973
         df = DataFrame(vals, index=idx)
         out = df.to_json(orient="table")
         result = pd.read_json(out, orient="table")

From b4ac6aa66dcd5e448a80b01b44a6ce6494ffef90 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Wed, 16 Sep 2020 09:31:44 +0200
Subject: [PATCH 21/29] linting

---
 pandas/tests/indexes/period/test_astype.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/pandas/tests/indexes/period/test_astype.py b/pandas/tests/indexes/period/test_astype.py
index 20c4fa2cbf6c9..fa1617bdfaa52 100644
--- a/pandas/tests/indexes/period/test_astype.py
+++ b/pandas/tests/indexes/period/test_astype.py
@@ -3,7 +3,6 @@
 
 from pandas import (
     CategoricalIndex,
-    DataFrame,
     DatetimeIndex,
     Index,
     Int64Index,
@@ -12,7 +11,6 @@
     PeriodIndex,
     Timedelta,
     UInt64Index,
-    date_range,
     period_range,
 )
 import pandas._testing as tm

From bae0a3079c98f96e7ef3cf2ad776b173b133a754 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Sat, 26 Sep 2020 09:13:33 +0200
Subject: [PATCH 22/29] test common terms

---
 pandas/tests/frame/methods/test_astype.py | 33 +++++++++++------------
 1 file changed, 15 insertions(+), 18 deletions(-)

diff --git a/pandas/tests/frame/methods/test_astype.py b/pandas/tests/frame/methods/test_astype.py
index 7363a60598b05..f93c7549ff57a 100644
--- a/pandas/tests/frame/methods/test_astype.py
+++ b/pandas/tests/frame/methods/test_astype.py
@@ -591,26 +591,23 @@ def test_astype_ignores_errors_for_extension_dtypes(self, df, errors):
     def test_astype_tz_conversion(self):
         # GH 35973
         val = {"tz": date_range("2020-08-30", freq="d", periods=2, tz="Europe/London")}
-        df, df2 = DataFrame(val), DataFrame(val)
-        df2["tz"] = df2["tz"].dt.tz_convert("Europe/Berlin")
+        result, expected = DataFrame(val), DataFrame(val)
 
-        tm.assert_frame_equal(df.astype({"tz": "datetime64[ns, Europe/Berlin]"}), df2)
+        result = expected.astype({"tz": "datetime64[ns, Europe/Berlin]"})
+        expected["tz"] = expected["tz"].dt.tz_convert("Europe/Berlin")
+
+        tm.assert_frame_equal(result, expected)
 
     @pytest.mark.parametrize("tz", ["UTC", "Europe/Berlin"])
     def test_astype_tz_object_conversion(self, tz):
         # GH 35973
-        # Test UTC, non-UTC inferred object to an original and specified tz.
-        vals = {
-            "timezones": date_range(
-                "2020-08-30", freq="d", periods=2, tz="Europe/London"
-            )
-        }
-        base = DataFrame(vals)
-
-        # convert base to input test param and then to object dtype
-        result = base.astype({"timezones": "datetime64[ns, {}]".format(tz)}).astype(
-            {"timezones": "object"}
-        )
-        # test conversion of object dtype to a specified tz, different to inferred.
-        result = result.astype({"timezones": "datetime64[ns, Europe/London]"})
-        tm.assert_frame_equal(base, result)
+        val = {"tz": date_range("2020-08-30", freq="d", periods=2, tz="Europe/London")}
+        expected = DataFrame(val)
+
+        # convert expected to object dtype from other tz str (independently tested)
+        result = expected.astype({"tz": f"datetime64[ns, {tz}]"})
+        result = result.astype({"tz": "object"})
+
+        # do real test: object dtype to a specified tz, different from construction tz.
+        result = result.astype({"tz": "datetime64[ns, Europe/London]"})
+        tm.assert_frame_equal(result, expected)

From 2f368260df5a488cc941bc79ece486b8f890ed12 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Sat, 26 Sep 2020 09:15:14 +0200
Subject: [PATCH 23/29] test common terms

---
 pandas/tests/frame/methods/test_astype.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/frame/methods/test_astype.py b/pandas/tests/frame/methods/test_astype.py
index f93c7549ff57a..467675343dc5a 100644
--- a/pandas/tests/frame/methods/test_astype.py
+++ b/pandas/tests/frame/methods/test_astype.py
@@ -591,7 +591,7 @@ def test_astype_ignores_errors_for_extension_dtypes(self, df, errors):
     def test_astype_tz_conversion(self):
         # GH 35973
         val = {"tz": date_range("2020-08-30", freq="d", periods=2, tz="Europe/London")}
-        result, expected = DataFrame(val), DataFrame(val)
+        expected = DataFrame(val)
 
         result = expected.astype({"tz": "datetime64[ns, Europe/Berlin]"})
         expected["tz"] = expected["tz"].dt.tz_convert("Europe/Berlin")

From 54da03fe83820515fc0cb2b2634e9331f0e2a338 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Tue, 29 Sep 2020 23:19:57 +0200
Subject: [PATCH 24/29] uncomment previous test now working.

---
 pandas/tests/io/json/test_json_table_schema.py | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/pandas/tests/io/json/test_json_table_schema.py b/pandas/tests/io/json/test_json_table_schema.py
index d94b48d4b4028..af0d3098a0367 100644
--- a/pandas/tests/io/json/test_json_table_schema.py
+++ b/pandas/tests/io/json/test_json_table_schema.py
@@ -692,7 +692,8 @@ def test_read_json_table_orient(self, index_nm, vals, recwarn):
 
     @pytest.mark.parametrize("index_nm", [None, "idx", "index"])
     @pytest.mark.parametrize(
-        "vals", [{"timedeltas": pd.timedelta_range("1H", periods=4, freq="T")}],
+        "vals",
+        [{"timedeltas": pd.timedelta_range("1H", periods=4, freq="T")}],
     )
     def test_read_json_table_orient_raises(self, index_nm, vals, recwarn):
         df = DataFrame(vals, index=pd.Index(range(4), name=index_nm))
@@ -704,7 +705,14 @@ def test_read_json_table_orient_raises(self, index_nm, vals, recwarn):
         "idx",
         [
             pd.Index(range(4)),
-            pd.Index(pd.date_range("2020-08-30", freq="d", periods=4,), freq=None),
+            pd.Index(
+                pd.date_range(
+                    "2020-08-30",
+                    freq="d",
+                    periods=4,
+                ),
+                freq=None,
+            ),
             pd.Index(
                 pd.date_range("2020-08-30", freq="d", periods=4, tz="US/Central"),
                 freq=None,
@@ -747,8 +755,7 @@ def test_comprehensive(self):
                 "E": pd.Series(pd.Categorical(["a", "b", "c", "c"])),
                 "F": pd.Series(pd.Categorical(["a", "b", "c", "c"], ordered=True)),
                 "G": [1.1, 2.2, 3.3, 4.4],
-                # 'H': pd.date_range('2016-01-01', freq='d', periods=4,
-                #                   tz='US/Central'),
+                "H": pd.date_range("2016-01-01", freq="d", periods=4, tz="US/Central"),
                 "I": [True, False, False, True],
             },
             index=pd.Index(range(4), name="idx"),

From 4fe7f41c48d284ac8edc4e13333655d6b929e5c5 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Wed, 30 Sep 2020 17:56:19 +0200
Subject: [PATCH 25/29] double quotes error

---
 doc/source/whatsnew/v1.2.0.rst | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/doc/source/whatsnew/v1.2.0.rst b/doc/source/whatsnew/v1.2.0.rst
index 3ee60e3afb7b3..0ea571653a418 100644
--- a/doc/source/whatsnew/v1.2.0.rst
+++ b/doc/source/whatsnew/v1.2.0.rst
@@ -120,9 +120,9 @@ Other enhancements
 - ``Styler`` now allows direct CSS class name addition to individual data cells (:issue:`36159`)
 - :meth:`Rolling.mean()` and :meth:`Rolling.sum()` use Kahan summation to calculate the mean to avoid numerical problems (:issue:`10319`, :issue:`11645`, :issue:`13254`, :issue:`32761`, :issue:`36031`)
 - :meth:`DatetimeIndex.searchsorted`, :meth:`TimedeltaIndex.searchsorted`, :meth:`PeriodIndex.searchsorted`, and :meth:`Series.searchsorted` with datetimelike dtypes will now try to cast string arguments (listlike and scalar) to the matching datetimelike type (:issue:`36346`)
-- :meth:`to_json` now implements timezones parsing for when orient structure is `table`.
-- :meth:`read_json` now implements timezones parsing for when orient structure is `table`.
-- :meth:`astype` now attempts to convert to `datetime64[ns, tz]` directly from `object` with inferred timezone from string (:issue:`35973`).
+- :meth:`to_json` now implements timezones parsing for when orient structure is 'table'.
+- :meth:`read_json` now implements timezones parsing for when orient structure is 'table'.
+- :meth:`astype` now attempts to convert to 'datetime64[ns, tz]' directly from 'object' with inferred timezone from string (:issue:`35973`).
 -
 
 .. _whatsnew_120.api_breaking.python:

From f0fe4e461ab5c634fc27c9ab0cd758260ab4bbb9 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Thu, 1 Oct 2020 07:33:47 +0200
Subject: [PATCH 26/29] restart tests

---
 doc/source/whatsnew/v1.2.0.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/source/whatsnew/v1.2.0.rst b/doc/source/whatsnew/v1.2.0.rst
index 0ea571653a418..e5b5b194c668f 100644
--- a/doc/source/whatsnew/v1.2.0.rst
+++ b/doc/source/whatsnew/v1.2.0.rst
@@ -120,8 +120,8 @@ Other enhancements
 - ``Styler`` now allows direct CSS class name addition to individual data cells (:issue:`36159`)
 - :meth:`Rolling.mean()` and :meth:`Rolling.sum()` use Kahan summation to calculate the mean to avoid numerical problems (:issue:`10319`, :issue:`11645`, :issue:`13254`, :issue:`32761`, :issue:`36031`)
 - :meth:`DatetimeIndex.searchsorted`, :meth:`TimedeltaIndex.searchsorted`, :meth:`PeriodIndex.searchsorted`, and :meth:`Series.searchsorted` with datetimelike dtypes will now try to cast string arguments (listlike and scalar) to the matching datetimelike type (:issue:`36346`)
-- :meth:`to_json` now implements timezones parsing for when orient structure is 'table'.
-- :meth:`read_json` now implements timezones parsing for when orient structure is 'table'.
+- :meth:`to_json` now implements timezones parsing when orient structure is 'table'.
+- :meth:`read_json` now implements timezones parsing when orient structure is 'table'.
 - :meth:`astype` now attempts to convert to 'datetime64[ns, tz]' directly from 'object' with inferred timezone from string (:issue:`35973`).
 -
 

From 8a82832c54d6968948f8874fa1eba46d15386f1e Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Thu, 1 Oct 2020 12:42:26 +0200
Subject: [PATCH 27/29] restart tests

---
 pandas/tests/io/json/test_json_table_schema.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/io/json/test_json_table_schema.py b/pandas/tests/io/json/test_json_table_schema.py
index af0d3098a0367..c9820901a5adb 100644
--- a/pandas/tests/io/json/test_json_table_schema.py
+++ b/pandas/tests/io/json/test_json_table_schema.py
@@ -755,7 +755,8 @@ def test_comprehensive(self):
                 "E": pd.Series(pd.Categorical(["a", "b", "c", "c"])),
                 "F": pd.Series(pd.Categorical(["a", "b", "c", "c"], ordered=True)),
                 "G": [1.1, 2.2, 3.3, 4.4],
-                "H": pd.date_range("2016-01-01", freq="d", periods=4, tz="US/Central"),
+                # 'H': pd.date_range('2016-01-01', freq='d', periods=4,
+                #                   tz='US/Central'),
                 "I": [True, False, False, True],
             },
             index=pd.Index(range(4), name="idx"),

From d44a267d0241e679feb3b3e2fb5b832d8bfd7ffb Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Fri, 9 Oct 2020 16:38:13 +0200
Subject: [PATCH 28/29] fix whats new comments

---
 doc/source/whatsnew/v1.2.0.rst | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/doc/source/whatsnew/v1.2.0.rst b/doc/source/whatsnew/v1.2.0.rst
index 55c6f862bf092..f47df0f338c87 100644
--- a/doc/source/whatsnew/v1.2.0.rst
+++ b/doc/source/whatsnew/v1.2.0.rst
@@ -188,9 +188,6 @@ Other enhancements
 - ``Styler`` now allows direct CSS class name addition to individual data cells (:issue:`36159`)
 - :meth:`Rolling.mean()` and :meth:`Rolling.sum()` use Kahan summation to calculate the mean to avoid numerical problems (:issue:`10319`, :issue:`11645`, :issue:`13254`, :issue:`32761`, :issue:`36031`)
 - :meth:`DatetimeIndex.searchsorted`, :meth:`TimedeltaIndex.searchsorted`, :meth:`PeriodIndex.searchsorted`, and :meth:`Series.searchsorted` with datetimelike dtypes will now try to cast string arguments (listlike and scalar) to the matching datetimelike type (:issue:`36346`)
-- :meth:`to_json` now implements timezones parsing when orient structure is 'table'.
-- :meth:`read_json` now implements timezones parsing when orient structure is 'table'.
-- :meth:`astype` now attempts to convert to 'datetime64[ns, tz]' directly from 'object' with inferred timezone from string (:issue:`35973`).
 -
 - Added methods :meth:`IntegerArray.prod`, :meth:`IntegerArray.min`, and :meth:`IntegerArray.max` (:issue:`33790`)
 - Where possible :meth:`RangeIndex.difference` and :meth:`RangeIndex.symmetric_difference` will return :class:`RangeIndex` instead of :class:`Int64Index` (:issue:`36564`)
@@ -340,6 +337,8 @@ Datetimelike
 - Bug in :class:`DatetimeIndex.shift` incorrectly raising when shifting empty indexes (:issue:`14811`)
 - :class:`Timestamp` and :class:`DatetimeIndex` comparisons between timezone-aware and timezone-naive objects now follow the standard library ``datetime`` behavior, returning ``True``/``False`` for ``!=``/``==`` and raising for inequality comparisons (:issue:`28507`)
 - Bug in :meth:`DatetimeIndex.equals` and :meth:`TimedeltaIndex.equals` incorrectly considering ``int64`` indexes as equal (:issue:`36744`)
+- :meth:`to_json` and :meth:`read_json` now implements timezones parsing when orient structure is 'table'.
+- :meth:`astype` now attempts to convert to 'datetime64[ns, tz]' directly from 'object' with inferred timezone from string (:issue:`35973`).
 
 Timedelta
 ^^^^^^^^^

From 4a1fc868b2d16bfee721e052eb9bd4b08d07fc56 Mon Sep 17 00:00:00 2001
From: "JHM Darbyshire (iMac)" <attack68@users.noreply.github.com>
Date: Fri, 9 Oct 2020 16:50:25 +0200
Subject: [PATCH 29/29] rephrased test

---
 pandas/tests/frame/methods/test_astype.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pandas/tests/frame/methods/test_astype.py b/pandas/tests/frame/methods/test_astype.py
index 467675343dc5a..f05c90f37ea8a 100644
--- a/pandas/tests/frame/methods/test_astype.py
+++ b/pandas/tests/frame/methods/test_astype.py
@@ -591,11 +591,11 @@ def test_astype_ignores_errors_for_extension_dtypes(self, df, errors):
     def test_astype_tz_conversion(self):
         # GH 35973
         val = {"tz": date_range("2020-08-30", freq="d", periods=2, tz="Europe/London")}
-        expected = DataFrame(val)
+        df = DataFrame(val)
+        result = df.astype({"tz": "datetime64[ns, Europe/Berlin]"})
 
-        result = expected.astype({"tz": "datetime64[ns, Europe/Berlin]"})
+        expected = df
         expected["tz"] = expected["tz"].dt.tz_convert("Europe/Berlin")
-
         tm.assert_frame_equal(result, expected)
 
     @pytest.mark.parametrize("tz", ["UTC", "Europe/Berlin"])