Copy UVC input to Barbs.

QuLogic · QuLogic · commit b3bf7348057a · 2021-06-24T04:24:16.000-04:00
For the same reason as Quiver in #4250.
diff --git a/lib/matplotlib/quiver.py b/lib/matplotlib/quiver.py
@@ -1158,8 +1158,10 @@ def _make_barbs(self, u, v, nflags, nbarbs, half_barb, empty_flag, length,
         return barb_list
 
     def set_UVC(self, U, V, C=None):
-        self.u = ma.masked_invalid(U, copy=False).ravel()
-        self.v = ma.masked_invalid(V, copy=False).ravel()
+        # We need to ensure we have a copy, not a reference to an array that
+        # might change before draw().
+        self.u = ma.masked_invalid(U, copy=True).ravel()
+        self.v = ma.masked_invalid(V, copy=True).ravel()
 
         # Flip needs to have the same number of entries as everything else.
         # Use broadcast_to to avoid a bloated array of identical values.
@@ -1170,7 +1172,7 @@ def set_UVC(self, U, V, C=None):
             flip = self.flip
 
         if C is not None:
-            c = ma.masked_invalid(C, copy=False).ravel()
+            c = ma.masked_invalid(C, copy=True).ravel()
             x, y, u, v, c, flip = cbook.delete_masked_points(
                 self.x.ravel(), self.y.ravel(), self.u, self.v, c,
                 flip.ravel())
diff --git a/lib/matplotlib/tests/test_quiver.py b/lib/matplotlib/tests/test_quiver.py
@@ -202,6 +202,17 @@ def test_barbs_flip():
              flip_barb=Y < 0)
 
 
+def test_barb_copy():
+    fig, ax = plt.subplots()
+    u = np.array([1.1])
+    v = np.array([2.2])
+    b0 = ax.barbs([1], [1], u, v)
+    u[0] = 0
+    assert b0.u[0] == 1.1
+    v[0] = 0
+    assert b0.v[0] == 2.2
+
+
 def test_bad_masked_sizes():
     """Test error handling when given differing sized masked arrays."""
     x = np.arange(3)
