Backport PR #9705: Fix scatterplot categorical support

dstansby · MeeseeksDev[bot] · commit b11fb2f2618b · 2017-11-07T10:37:53.000Z
diff --git a/lib/matplotlib/category.py b/lib/matplotlib/category.py
@@ -40,6 +40,12 @@ def convert(value, unit, axis):
         """Uses axis.unit_data map to encode
         data as floats
         """
+        value = np.atleast_1d(value)
+        # try and update from here....
+        if hasattr(axis.unit_data, 'update'):
+            for val in value:
+                if isinstance(val, six.string_types):
+                    axis.unit_data.update(val)
         vmap = dict(zip(axis.unit_data.seq, axis.unit_data.locs))
 
         if isinstance(value, six.string_types):
diff --git a/lib/matplotlib/tests/test_category.py b/lib/matplotlib/tests/test_category.py
@@ -243,3 +243,16 @@ def test_plot_update(self):
         unit_data = MockUnitData(list(zip(labels, ticks)))
 
         self.axis_test(ax.yaxis, ticks, labels, unit_data)
+
+    def test_scatter_update(self):
+        fig, ax = plt.subplots()
+
+        ax.scatter(['a', 'b'], [0., 3.])
+        ax.scatter(['a', 'b', 'd'], [1., 2., 3.])
+        ax.scatter(['b', 'c', 'd'], [4., 1., 2.])
+        fig.canvas.draw()
+
+        labels = ['a', 'b', 'd', 'c']
+        ticks = [0, 1, 2, 3]
+        unit_data = MockUnitData(list(zip(labels, ticks)))
+        self.axis_test(ax.xaxis, ticks, labels, unit_data)
