matplotlib · QuLogic · Dec 3, 2018 · Sep 26, 2018 · Sep 30, 2018 · Oct 2, 2018
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -3122,8 +3122,8 @@ def set_xlim(self, left=None, right=None, emit=True, auto=False,
             limit unchanged.
 
             The left and right xlims may be passed as the tuple
-            (`left`, `right`) as the first positional argument (or as
-            the `left` keyword argument).
+            (*left*, *right*) as the first positional argument (or as
+            the *left* keyword argument).
 
         right : scalar, optional
             The right xlim in data coordinates. Passing *None* leaves the
@@ -3169,7 +3169,7 @@ def set_xlim(self, left=None, right=None, emit=True, auto=False,
         >>> set_xlim(right=right_lim)
 
         Limits may be passed in reverse order to flip the direction of
-        the x-axis. For example, suppose ``x`` represents the number of
+        the x-axis. For example, suppose *x* represents the number of
         years before present. The x-axis limits might be set like the
         following so 5000 years ago is on the left of the plot and the
         present is on the right.
@@ -3510,15 +3510,15 @@ def set_ylim(self, bottom=None, top=None, emit=True, auto=False,
             limit unchanged.
 
             The bottom and top ylims may be passed as the tuple
-            (`bottom`, `top`) as the first positional argument (or as
-            the `bottom` keyword argument).
+            (*bottom*, *top*) as the first positional argument (or as
+            the *bottom* keyword argument).
 
         top : scalar, optional
             The top ylim in data coordinates. Passing *None* leaves the
             limit unchanged.
 
         emit : bool, optional
-            Whether to notify observers of limit change (default: True).
+            Whether to notify observers of limit change (default: ``True``).
 
         auto : bool or None, optional
             Whether to turn on autoscaling of the y-axis. *True* turns on,

diff --git a/lib/matplotlib/projections/polar.py b/lib/matplotlib/projections/polar.py
@@ -2,6 +2,7 @@
 import types
 
 import numpy as np
+import warnings
 
 from matplotlib.axes import Axes
 import matplotlib.axis as maxis
@@ -57,7 +58,8 @@ def transform_non_affine(self, tr):
             t += self._axis.get_theta_offset()
 
         if self._use_rmin and self._axis is not None:
-            r = r - self._axis.get_rorigin()
+            r = (r - self._axis.get_rorigin()) * self._axis.get_rsign()
+
         mask = r < 0
         x[:] = np.where(mask, np.nan, r * np.cos(t))
         y[:] = np.where(mask, np.nan, r * np.sin(t))
@@ -161,6 +163,7 @@ def transform_non_affine(self, xy):
 
         if self._use_rmin and self._axis is not None:
             r += self._axis.get_rorigin()
+            r *= self._axis.get_rsign()
 
         return np.concatenate((theta, r), 1)
     transform_non_affine.__doc__ = \
@@ -421,10 +424,9 @@ def __call__(self):
         # Ensure previous behaviour with full circle non-annular views.
         if self._axes:
             if _is_full_circle_rad(*self._axes.viewLim.intervalx):
-                rorigin = self._axes.get_rorigin()
+                rorigin = self._axes.get_rorigin() * self._axes.get_rsign()
                 if self._axes.get_rmin() <= rorigin:
                     show_all = False
-
         if show_all:
             return self.base()
         else:
@@ -444,7 +446,10 @@ def refresh(self):
 
     def view_limits(self, vmin, vmax):
         vmin, vmax = self.base.view_limits(vmin, vmax)
-        return mtransforms.nonsingular(min(0, vmin), vmax)
+        if vmax > vmin:
+            # this allows inverted r/y-lims
+            vmin = min(0, vmin)
+        return mtransforms.nonsingular(vmin, vmax)
 
 
 class _ThetaShift(mtransforms.ScaledTranslation):
@@ -767,7 +772,6 @@ def __str__(self):
     def get_points(self):
         if self._invalid:
             points = self._viewLim.get_points().copy()
-
             # Scale angular limits to work with Wedge.
             points[:, 0] *= 180 / np.pi
             if points[0, 0] > points[1, 0]:
@@ -992,8 +996,8 @@ def draw(self, *args, **kwargs):
         thetamin, thetamax = np.rad2deg(self._realViewLim.intervalx)
         if thetamin > thetamax:
             thetamin, thetamax = thetamax, thetamin
-        rmin, rmax = self._realViewLim.intervaly - self.get_rorigin()
-
+        rmin, rmax = ((self._realViewLim.intervaly - self.get_rorigin()) *
+                        self.get_rsign())
         if isinstance(self.patch, mpatches.Wedge):
             # Backwards-compatibility: Any subclassed Axes might override the
             # patch to not be the Wedge that PolarAxes uses.
@@ -1160,12 +1164,83 @@ def set_rorigin(self, rorigin):
     def get_rorigin(self):
         return self._originViewLim.y0
 
-    def set_rlim(self, *args, **kwargs):
+    def get_rsign(self):
+        return np.sign(self._originViewLim.y1 - self._originViewLim.y0)
+
+    def set_rlim(self, bottom=None, top=None, emit=True, auto=False, **kwargs):
+        """
+        See `~.polar.PolarAxes.set_ylim`.
+        """
         if 'rmin' in kwargs:
-            kwargs['ymin'] = kwargs.pop('rmin')
+            if bottom is None:
+                bottom = kwargs.pop('rmin')
+            else:
+                raise ValueError('Cannot supply both positional "bottom"'
+                                 'argument and kwarg "rmin"')
         if 'rmax' in kwargs:
-            kwargs['ymax'] = kwargs.pop('rmax')
-        return self.set_ylim(*args, **kwargs)
+            if top is None:
+                top = kwargs.pop('rmax')
+            else:
+                raise ValueError('Cannot supply both positional "top"'
+                                 'argument and kwarg "rmax"')
+        return self.set_ylim(bottom=bottom, top=top, emit=emit, auto=auto,
+                             **kwargs)
+
+    def set_ylim(self, bottom=None, top=None, emit=True, auto=False,
+                 *, ymin=None, ymax=None):
+        """
+        Set the data limits for the radial axis.
+
+        Parameters
+        ----------
+        bottom : scalar, optional
+            The bottom limit (default: None, which leaves the bottom
+            limit unchanged).
+            The bottom and top ylims may be passed as the tuple
+            (*bottom*, *top*) as the first positional argument (or as
+            the *bottom* keyword argument).
+
+        top : scalar, optional
+            The top limit (default: None, which leaves the top limit
+            unchanged).
+
+        emit : bool, optional
+            Whether to notify observers of limit change (default: True).
+
+        auto : bool or None, optional
+            Whether to turn on autoscaling of the y-axis. True turns on,
+            False turns off (default action), None leaves unchanged.
+
+        ymin, ymax : scalar, optional
+            These arguments are deprecated and will be removed in a future
+            version.  They are equivalent to *bottom* and *top* respectively,
+            and it is an error to pass both *ymin* and *bottom* or
+            *ymax* and *top*.
+
+        Returns
+        -------
+        ylimits : tuple
+            Returns the new y-axis limits as (*bottom*, *top*).
+
+        """
+
+        if ymin is not None:
+            if bottom is not None:
+                raise ValueError('Cannot supply both positional "bottom" '
+                                 'argument and kwarg "ymin"')
+            else:
+                bottom = ymin
+        if ymax is not None:
+            if top is not None:
+                raise ValueError('Cannot supply both positional "top" '
+                                 'argument and kwarg "ymax"')
+            else:
+                top = ymax
+        if top is None and len(bottom) == 2:
+            top = bottom[1]
+            bottom = bottom[0]
+
+        return super().set_ylim(bottom=bottom, top=top, emit=emit, auto=auto)
 
     def get_rlabel_position(self):
         """

diff --git a/lib/matplotlib/tests/baseline_images/test_axes/polar_invertedylim.png b/lib/matplotlib/tests/baseline_images/test_axes/polar_invertedylim.png
diff --git a/lib/matplotlib/tests/baseline_images/test_axes/polar_invertedylim_rorigin.png b/lib/matplotlib/tests/baseline_images/test_axes/polar_invertedylim_rorigin.png
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -726,6 +726,23 @@ def test_polar_rorigin():
     ax.set_rorigin(0.0)
 
 
+@image_comparison(baseline_images=['polar_invertedylim'], style='default',
+                   extensions=['png'])
+def test_polar_invertedylim():
+    fig = plt.figure()
+    ax = fig.add_axes([0.1, 0.1, 0.8, 0.8], polar=True)
+    ax.set_ylim(2, 0)
+
+
+@image_comparison(baseline_images=['polar_invertedylim_rorigin'],
+                  style='default', extensions=['png'])
+def test_polar_invertedylim_rorigin():
+    fig = plt.figure()
+    ax = fig.add_axes([0.1, 0.1, 0.8, 0.8], polar=True)
+    ax.set_ylim(2, 0)
+    ax.set_rorigin(3)
+
+
 @image_comparison(baseline_images=['polar_theta_position'], style='default')
 def test_polar_theta_position():
     r = np.arange(0, 3.0, 0.01)