BUG: Pandas can't restore index from parquet with offset-specified timezone pandas-dev#35997

Author: alippai

pandas/_libs/tslibs/timezones.pyx

@@ -1,4 +1,4 @@
-from datetime import timezone
+from datetime import timedelta, timezone
 
 from cpython.datetime cimport datetime, timedelta, tzinfo
 
@@ -103,7 +103,24 @@ cpdef inline tzinfo maybe_get_tz(object tz):
             if isinstance(tz, _dateutil_tzfile) and '.tar.gz' in tz._filename:
                 tz._filename = zone
         else:
-            tz = pytz.timezone(tz)
+            if tz[0] == '-':
+                hours = int(tz[1:3])
+                minutes = int(tz[4:6])
+                tz = timezone(-timedelta(hours=hours, minutes=minutes))
+            elif tz[0] == '+':
+                hours = int(tz[1:3])
+                minutes = int(tz[4:6])
+                tz = timezone(timedelta(hours=hours, minutes=minutes))
+            elif tz[0:4] == 'UTC-':
+                hours = int(tz[4:6])
+                minutes = int(tz[7:9])
+                tz = timezone(-timedelta(hours=hours, minutes=minutes))
+            elif tz[0:4] == 'UTC+':
+                hours = int(tz[4:6])
+                minutes = int(tz[7:9])
+                tz = timezone(timedelta(hours=hours, minutes=minutes))
+            else:
+                tz = pytz.timezone(tz)
     elif is_integer_object(tz):
         tz = pytz.FixedOffset(tz / 60)
     elif isinstance(tz, tzinfo):

pandas/tests/io/test_parquet.py

@@ -712,6 +712,12 @@ def test_timestamp_nanoseconds(self, pa):
         df = pd.DataFrame({"a": pd.date_range("2017-01-01", freq="1n", periods=10)})
         check_round_trip(df, pa, write_kwargs={"version": "2.0"})
 
+    @td.skip_if_no("pyarrow", min_version="0.14")
+    def test_timezone_aware_index(self, pa):
+        idx = [datetime.datetime.now(datetime.timezone.utc)]
+        df = pd.DataFrame(index=idx)
+        check_round_trip(df, pa, write_kwargs={"version": "2.0"})
+
     @td.skip_if_no("pyarrow", min_version="0.17")
     def test_filter_row_groups(self, pa):
         # https://github.com/pandas-dev/pandas/issues/26551
@@ -850,3 +856,15 @@ def test_empty_dataframe(self, fp):
         expected = df.copy()
         expected.index.name = "index"
         check_round_trip(df, fp, expected=expected)
+
+    def test_timezone_aware_index(self, fp):
+        idx = [
+            datetime.datetime.strptime(
+                "2019-01-04T16:41:24+0200", "%Y-%m-%dT%H:%M:%S%z"
+            )
+        ]
+        df = pd.DataFrame(index=idx)
+
+        expected = df.copy()
+        expected.index.name = "index"
+        check_round_trip(df, fp, expected=expected)