May 6, 2025 · May 6, 2025
diff --git a/doc/api/next_api_changes/removals/30015-DS.rst b/doc/api/next_api_changes/removals/30015-DS.rst
 *nth_coord* parameter to axisartist helpers for fixed axis
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 Helper APIs in `.axisartist` for generating a "fixed" axis on rectilinear axes
 (`.FixedAxisArtistHelperRectilinear`) no longer take a *nth_coord* parameter.
 That parameter is entirely inferred from the (required) *loc* parameter.

 For curvilinear axes, the *nth_coord* parameter remains supported (it affects
 the *ticks*, not the axis position itself), but it is now keyword-only.
diff --git a/lib/mpl_toolkits/axisartist/axislines.py b/lib/mpl_toolkits/axisartist/axislines.py
 class _FixedAxisArtistHelperBase(_AxisArtistHelperBase):
    """Helper class for a fixed (in the axes coordinate) axis."""

    @_api.delete_parameter("3.9", "nth_coord")
    def __init__(self, loc, nth_coord=None):
    def __init__(self, loc):
        """``nth_coord = 0``: x-axis; ``nth_coord = 1``: y-axis."""
        super().__init__(_api.check_getitem(
            {"bottom": 0, "top": 0, "left": 1, "right": 1}, loc=loc))

 class FixedAxisArtistHelperRectilinear(_FixedAxisArtistHelperBase):

    @_api.delete_parameter("3.9", "nth_coord")
    def __init__(self, axes, loc, nth_coord=None):
        """
        nth_coord = along which coordinate value varies
        in 2D, nth_coord = 0 ->  x axis, nth_coord = 1 -> y axis
        """
    def __init__(self, axes, loc):
        super().__init__(loc)
        self.axis = [axes.xaxis, axes.yaxis][self.nth_coord]

        super().__init__()
        self.axes = axes

    @_api.delete_parameter(
        "3.9", "nth_coord", addendum="'nth_coord' is now inferred from 'loc'.")
    def new_fixed_axis(
            self, loc, nth_coord=None, axis_direction=None, offset=None, axes=None):
        self, loc, *, axis_direction=None, offset=None, axes=None
    ):
        if axes is None:
            _api.warn_external(
                "'new_fixed_axis' explicitly requires the axes keyword.")
diff --git a/lib/mpl_toolkits/axisartist/grid_helper_curvelinear.py b/lib/mpl_toolkits/axisartist/grid_helper_curvelinear.py
        self.grid_finder.update(**kwargs)
        self._old_limits = None  # Force revalidation.

    @_api.make_keyword_only("3.9", "nth_coord")
    def new_fixed_axis(
            self, loc, nth_coord=None, axis_direction=None, offset=None, axes=None):
        self, loc, *, axis_direction=None, offset=None, axes=None, nth_coord=None
    ):
        if axes is None:
            axes = self.axes
        if axis_direction is None:
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,9 @@
		nth_coord parameter to axisartist helpers for fixed axis
		~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

		Helper APIs in `.axisartist` for generating a "fixed" axis on rectilinear axes
		(`.FixedAxisArtistHelperRectilinear`) no longer take a nth_coord parameter.
		That parameter is entirely inferred from the (required) loc parameter.

		For curvilinear axes, the nth_coord parameter remains supported (it affects
		the ticks, not the axis position itself), but it is now keyword-only.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -120,8 +120,7 @@ def _to_xy(self, values, const):
		class _FixedAxisArtistHelperBase(_AxisArtistHelperBase):
		"""Helper class for a fixed (in the axes coordinate) axis."""

		@_api.delete_parameter("3.9", "nth_coord")
		def __init__(self, loc, nth_coord=None):
		def __init__(self, loc):
		"""``nth_coord = 0``: x-axis; ``nth_coord = 1``: y-axis."""
		super().__init__(_api.check_getitem(
		{"bottom": 0, "top": 0, "left": 1, "right": 1}, loc=loc))
Expand DownExpand Up		@@ -171,12 +170,7 @@ def get_line(self, axes):

		class FixedAxisArtistHelperRectilinear(_FixedAxisArtistHelperBase):

		@_api.delete_parameter("3.9", "nth_coord")
		def __init__(self, axes, loc, nth_coord=None):
		"""
		nth_coord = along which coordinate value varies
		in 2D, nth_coord = 0 -> x axis, nth_coord = 1 -> y axis
		"""
		def __init__(self, axes, loc):
		super().__init__(loc)
		self.axis = [axes.xaxis, axes.yaxis][self.nth_coord]

Expand DownExpand Up		@@ -311,10 +305,9 @@ def __init__(self, axes):
		super().__init__()
		self.axes = axes

		@_api.delete_parameter(
		"3.9", "nth_coord", addendum="'nth_coord' is now inferred from 'loc'.")
		def new_fixed_axis(
		self, loc, nth_coord=None, axis_direction=None, offset=None, axes=None):
		self, loc, *, axis_direction=None, offset=None, axes=None
		):
		if axes is None:
		_api.warn_external(
		"'new_fixed_axis' explicitly requires the axes keyword.")
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -316,9 +316,9 @@ def update_grid_finder(self, aux_trans=None, **kwargs):
		self.grid_finder.update(**kwargs)
		self._old_limits = None # Force revalidation.

		@_api.make_keyword_only("3.9", "nth_coord")
		def new_fixed_axis(
		self, loc, nth_coord=None, axis_direction=None, offset=None, axes=None):
		self, loc, *, axis_direction=None, offset=None, axes=None, nth_coord=None
		):
		if axes is None:
		axes = self.axes
		if axis_direction is None:
Expand Down