Add tests and fix for Datetime64TZFormatter

Author: BryanCutler

pandas/io/formats/format.py

@@ -1526,18 +1526,17 @@ def _format_strings(self) -> List[str]:
             flat_values = DatetimeIndex(flat_values)
 
         if self.formatter is not None and callable(self.formatter):
-            flat_str_values = np.array([self.formatter(x) for x in flat_values])
-            fmt_values = flat_str_values
+            fmt_values = [self.formatter(x) for x in flat_values]
         else:
             fmt_values = flat_values._data._format_native_types(
                 na_rep=self.nat_rep, date_format=self.date_format
             )
-        fmt_values = fmt_values.reshape(values.shape)
 
-        if len(fmt_values.shape) > 1:
-            nested_string_formatter = GenericArrayFormatter(fmt_values)
-            fmt_values = nested_string_formatter.get_result()
-        else:
+        if len(values.shape) > 1:
+            fmt_values = np.asarray(fmt_values).reshape(values.shape)
+            nested_formatter = GenericArrayFormatter(fmt_values)
+            fmt_values = nested_formatter.get_result()
+        elif isinstance(fmt_values, np.ndarray):
             fmt_values = fmt_values.tolist()
 
         return fmt_values
@@ -1718,18 +1717,16 @@ def _format_strings(self) -> List[str]:
         flat_values = values.ravel()
 
         ido = is_dates_only(flat_values)
-
         formatter = self.formatter or get_format_datetime64(
             ido, date_format=self.date_format
         )
 
-        fmt_values = np.array([formatter(x) for x in flat_values]).reshape(values.shape)
+        fmt_values = [formatter(x) for x in flat_values]
 
-        if len(fmt_values.shape) > 1:
-            nested_string_formatter = GenericArrayFormatter(fmt_values)
-            fmt_values = nested_string_formatter.get_result()
-        else:
-            fmt_values = fmt_values.tolist()
+        if len(values.shape) > 1:
+            fmt_values = np.asarray(fmt_values).reshape(values.shape)
+            nested_formatter = GenericArrayFormatter(fmt_values)
+            fmt_values = nested_formatter.get_result()
 
         return fmt_values
 

pandas/tests/io/formats/test_format.py

@@ -3146,7 +3146,13 @@ def format_func(t):
 class TestDatetime64TZFormatter:
     def test_mixed(self):
         utc = dateutil.tz.tzutc()
-        x = Series([datetime(2013, 1, 1, tzinfo=utc), datetime(2013, 1, 1, 12, tzinfo=utc), pd.NaT])
+        x = Series(
+            [
+                datetime(2013, 1, 1, tzinfo=utc),
+                datetime(2013, 1, 1, 12, tzinfo=utc),
+                pd.NaT,
+            ]
+        )
         result = fmt.Datetime64TZFormatter(x).get_result()
         assert len(result) == 3
         assert result[0].strip() == "2013-01-01 00:00:00+00:00"
@@ -3163,20 +3169,26 @@ def test_datetime64formatter_1d_array(self):
         assert result[2].strip() == "2018-01-01 02:00:00-08:00"
 
     def test_datetime64formatter_2d_array(self):
-        x = pd.date_range("2018-01-01", periods=10, freq="H", tz="US/Pacific").to_numpy()
+        x = pd.date_range(
+            "2018-01-01", periods=10, freq="H", tz="US/Pacific"
+        ).to_numpy()
         formatter = fmt.Datetime64TZFormatter(x.reshape((5, 2)))
         result = formatter.get_result()
         assert len(result) == 5
         assert result[0].strip() == "[2018-01-01 00:00:00-08:00, 2018-01-01 01:00:0..."
         assert result[4].strip() == "[2018-01-01 08:00:00-08:00, 2018-01-01 09:00:0..."
 
     def test_datetime64formatter_2d_array_format_func(self):
-        x = pd.date_range("2018-01-01", periods=16, freq="H", tz="US/Pacific").to_numpy()
+        x = pd.date_range(
+            "2018-01-01", periods=16, freq="H", tz="US/Pacific"
+        ).to_numpy()
 
         def format_func(t):
             return t.strftime("%H-%m %Z")
 
-        formatter = fmt.Datetime64TZFormatter(x.reshape((4, 2, 2)), formatter=format_func)
+        formatter = fmt.Datetime64TZFormatter(
+            x.reshape((4, 2, 2)), formatter=format_func
+        )
         result = formatter.get_result()
         assert len(result) == 4
         assert result[0].strip() == "[[00-01 PST, 01-01 PST], [02-01 PST, 03-01 PST]]"