Fix axes vlines and hlines using wrong coordinates

Author: robrighter

lib/matplotlib/axes/_axes.py

@@ -1101,14 +1101,25 @@ def hlines(self, y, xmin, xmax, colors=None, linestyles='solid',
             # Extreme values of xmin/xmax/y.  Using masked_verts here handles
             # the case of y being a masked *object* array (as can be generated
             # e.g. by errorbar()), which would make nanmin/nanmax stumble.
-            minx = np.nanmin(masked_verts[..., 0])
-            maxx = np.nanmax(masked_verts[..., 0])
-            miny = np.nanmin(masked_verts[..., 1])
-            maxy = np.nanmax(masked_verts[..., 1])
+            updatex = True
+            updatey = True
+            if self.name == "rectilinear":
+                datalim = lines.get_datalim(self.transData)
+                t = lines.get_transform()
+                updatex, updatey = t.contains_branch_seperately(self.transData)
+                minx = np.nanmin(datalim.xmin)
+                maxx = np.nanmax(datalim.xmax)
+                miny = np.nanmin(datalim.ymin)
+                maxy = np.nanmax(datalim.ymax)
+            else:
+                minx = np.nanmin(masked_verts[..., 0])
+                maxx = np.nanmax(masked_verts[..., 0])
+                miny = np.nanmin(masked_verts[..., 1])
+                maxy = np.nanmax(masked_verts[..., 1])
+
             corners = (minx, miny), (maxx, maxy)
-            self.update_datalim(corners)
+            self.update_datalim(corners, updatex, updatey)
             self._request_autoscale_view()
-
         return lines
 
     @_preprocess_data(replace_names=["x", "ymin", "ymax", "colors"],
@@ -1181,14 +1192,25 @@ def vlines(self, x, ymin, ymax, colors=None, linestyles='solid',
             # Extreme values of x/ymin/ymax.  Using masked_verts here handles
             # the case of x being a masked *object* array (as can be generated
             # e.g. by errorbar()), which would make nanmin/nanmax stumble.
-            minx = np.nanmin(masked_verts[..., 0])
-            maxx = np.nanmax(masked_verts[..., 0])
-            miny = np.nanmin(masked_verts[..., 1])
-            maxy = np.nanmax(masked_verts[..., 1])
+            updatex = True
+            updatey = True
+            if self.name == "rectilinear":
+                datalim = lines.get_datalim(self.transData)
+                t = lines.get_transform()
+                updatex, updatey = t.contains_branch_seperately(self.transData)
+                minx = np.nanmin(datalim.xmin)
+                maxx = np.nanmax(datalim.xmax)
+                miny = np.nanmin(datalim.ymin)
+                maxy = np.nanmax(datalim.ymax)
+            else:
+                minx = np.nanmin(masked_verts[..., 0])
+                maxx = np.nanmax(masked_verts[..., 0])
+                miny = np.nanmin(masked_verts[..., 1])
+                maxy = np.nanmax(masked_verts[..., 1])
+
             corners = (minx, miny), (maxx, maxy)
-            self.update_datalim(corners)
+            self.update_datalim(corners, updatex, updatey)
             self._request_autoscale_view()
-
         return lines
 
     @_preprocess_data(replace_names=["positions", "lineoffsets",

lib/matplotlib/tests/baseline_images/test_axes/vlines_hlines_blended_transform.png

@@ -4920,6 +4920,20 @@ def test_lines_with_colors(fig_test, fig_ref, data):
                                         colors=expect_color, linewidth=5)
 
 
+@image_comparison(['vlines_hlines_blended_transform'],
+                  extensions=['png'], style='mpl20')
+def test_vlines_hlines_blended_transform():
+    t = np.arange(5.0, 10.0, 0.1)
+    s = np.exp(-t) + np.sin(2 * np.pi * t) + 10
+    fig, (hax, vax) = plt.subplots(2, 1, figsize=(6, 6))
+    hax.plot(t, s, '^')
+    hax.hlines([10, 9], xmin=0, xmax=0.5,
+               transform=hax.get_yaxis_transform(), colors='r')
+    vax.plot(t, s, '^')
+    vax.vlines([6, 7], ymin=0, ymax=0.15, transform=vax.get_xaxis_transform(),
+               colors='r')
+
+
 @image_comparison(['step_linestyle', 'step_linestyle'], remove_text=True,
                   tol=0.2)
 def test_step_linestyle():