Backport PR #65436 on branch 3.0.x (Account for privatization of matplotlib Formatter.locs attribute) (#65520)

Author: ayshih

pandas/plotting/_matplotlib/converter.py

@@ -182,7 +182,7 @@ def default_units(x, axis) -> str:
 # time formatter
 class TimeFormatter(mpl.ticker.Formatter):  # pyright: ignore[reportAttributeAccessIssue]
     def __init__(self, locs) -> None:
-        self.locs = locs
+        self.set_locs(locs)
 
     def __call__(self, x, pos: int | None = 0) -> str:
         """
@@ -1046,7 +1046,7 @@ def __init__(
         freq = to_offset(freq, is_period=True)
         self.format = None
         self.freq = freq
-        self.locs: list[Any] = []  # unused, for matplotlib compat
+        super().set_locs([])  # unused, for matplotlib compat
         self.formatdict: dict[Any, Any] | None = None
         self.isminor = minor_locator
         self.isdynamic = dynamic_mode
@@ -1070,7 +1070,7 @@ def set_locs(self, locs) -> None:
         # don't actually use the locs. This is just needed to work with
         # matplotlib. Force to use vmin, vmax
 
-        self.locs = locs
+        super().set_locs(locs)
 
         (vmin, vmax) = tuple(self.axis.get_view_interval())
         if vmax < vmin: