Merge pull request #15360 from meeseeksmachine/auto-backport-of-pr-15258-on-v3.2.x

dstansby · web-flow · commit 7f4f435f91a5 · 2019-10-02T22:48:07.000+01:00
Backport PR #15258 on branch v3.2.x (Don't fallback to view limits when autoscale()ing no data.)
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -2409,17 +2409,9 @@ def handle_single_axis(scale, autoscaleon, shared_axes, interval,
                 dl.extend(y_finite)
 
             bb = mtransforms.BboxBase.union(dl)
-            # fall back on the viewlimits if this is not finite:
-            vl = None
-            if not np.isfinite(bb.intervalx).all():
-                vl = mtransforms.BboxBase.union([ax.viewLim for ax in shared])
-                bb.intervalx = vl.intervalx
-            if not np.isfinite(bb.intervaly).all():
-                if vl is None:
-                    vl = mtransforms.BboxBase.union(
-                        [ax.viewLim for ax in shared])
-                bb.intervaly = vl.intervaly
             x0, x1 = getattr(bb, interval)
+            # If x0 and x1 are non finite, use the locator to figure out
+            # default limits.
             locator = axis.get_major_locator()
             x0, x1 = locator.nonsingular(x0, x1)
 
@@ -3260,20 +3252,26 @@ def set_xscale(self, value, **kwargs):
             - `matplotlib.scale.SymmetricalLogScale`
             - `matplotlib.scale.LogitScale`
 
-
         Notes
         -----
         By default, Matplotlib supports the above mentioned scales.
         Additionally, custom scales may be registered using
         `matplotlib.scale.register_scale`. These scales can then also
         be used here.
         """
+        old_default_lims = (self.xaxis.get_major_locator()
+                            .nonsingular(-np.inf, np.inf))
         g = self.get_shared_x_axes()
         for ax in g.get_siblings(self):
             ax.xaxis._set_scale(value, **kwargs)
             ax._update_transScale()
             ax.stale = True
-        self._request_autoscale_view(scaley=False)
+        new_default_lims = (self.xaxis.get_major_locator()
+                            .nonsingular(-np.inf, np.inf))
+        if old_default_lims != new_default_lims:
+            # Force autoscaling now, to take advantage of the scale locator's
+            # nonsingular() before it possibly gets swapped out by the user.
+            self.autoscale_view(scaley=False)
 
     @cbook._make_keyword_only("3.2", "minor")
     def get_xticks(self, minor=False):
@@ -3645,20 +3643,26 @@ def set_yscale(self, value, **kwargs):
             - `matplotlib.scale.SymmetricalLogScale`
             - `matplotlib.scale.LogitScale`
 
-
         Notes
         -----
         By default, Matplotlib supports the above mentioned scales.
         Additionally, custom scales may be registered using
         `matplotlib.scale.register_scale`. These scales can then also
         be used here.
         """
+        old_default_lims = (self.yaxis.get_major_locator()
+                            .nonsingular(-np.inf, np.inf))
         g = self.get_shared_y_axes()
         for ax in g.get_siblings(self):
             ax.yaxis._set_scale(value, **kwargs)
             ax._update_transScale()
             ax.stale = True
-        self._request_autoscale_view(scalex=False)
+        new_default_lims = (self.yaxis.get_major_locator()
+                            .nonsingular(-np.inf, np.inf))
+        if old_default_lims != new_default_lims:
+            # Force autoscaling now, to take advantage of the scale locator's
+            # nonsingular() before it possibly gets swapped out by the user.
+            self.autoscale_view(scalex=False)
 
     @cbook._make_keyword_only("3.2", "minor")
     def get_yticks(self, minor=False):
diff --git a/lib/matplotlib/dates.py b/lib/matplotlib/dates.py
@@ -1118,6 +1118,10 @@ def nonsingular(self, vmin, vmax):
         Given the proposed upper and lower extent, adjust the range
         if it is too close to being singular (i.e. a range of ~0).
         """
+        if not np.isfinite(vmin) or not np.isfinite(vmax):
+            # Except if there is no data, then use 2000-2010 as default.
+            return (date2num(datetime.date(2000, 1, 1)),
+                    date2num(datetime.date(2010, 1, 1)))
         if vmax < vmin:
             vmin, vmax = vmax, vmin
         unit = self._get_unit()
@@ -1337,6 +1341,10 @@ def tick_values(self, vmin, vmax):
     def nonsingular(self, vmin, vmax):
         # whatever is thrown at us, we can scale the unit.
         # But default nonsingular date plots at an ~4 year period.
+        if not np.isfinite(vmin) or not np.isfinite(vmax):
+            # Except if there is no data, then use 2000-2010 as default.
+            return (date2num(datetime.date(2000, 1, 1)),
+                    date2num(datetime.date(2010, 1, 1)))
         if vmax < vmin:
             vmin, vmax = vmax, vmin
         if vmin == vmax:
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -2170,6 +2170,13 @@ def test_log_scales():
     ax.set_xscale('log', basex=9.0)
 
 
+def test_log_scales_no_data():
+    _, ax = plt.subplots()
+    ax.set(xscale="log", yscale="log")
+    ax.xaxis.set_major_locator(mticker.MultipleLocator(1))
+    assert ax.get_xlim() == ax.get_ylim() == (1, 10)
+
+
 def test_log_scales_invalid():
     fig = plt.figure()
     ax = fig.add_subplot(1, 1, 1)
diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -1710,7 +1710,19 @@ def raise_if_exceeds(self, locs):
         return locs
 
     def nonsingular(self, v0, v1):
-        """Expand a range as needed to avoid singularities."""
+        """
+        Adjust a range as needed to avoid singularities.
+
+        This method gets called during autoscaling, with ``(v0, v1)`` set to
+        the data limits on the axes if the axes contains any data, or
+        ``(-inf, +inf)`` if not.
+
+        - If ``v0 == v1`` (possibly up to some floating point slop), this
+          method returns an expanded interval around this value.
+        - If ``(v0, v1) == (-inf, +inf)``, this method returns appropriate
+          default view limits.
+        - Otherwise, ``(v0, v1)`` is returned without modification.
+        """
         return mtransforms.nonsingular(v0, v1, expander=.05)
 
     def view_limits(self, vmin, vmax):
