Add whats_new entry

Author: ericpre

doc/users/next_whats_new/add_EllipseCollection_setters.rst

@@ -0,0 +1,40 @@
+Add ``widths``, ``heights`` and ``angles`` setter to ``EllipseCollection``
+--------------------------------------------------------------------------
+
+The ``widths``, ``heights`` and ``angles`` values of the `~matplotlib.collections.EllipseCollection`
+can now be changed after the collection has been created.
+
+.. plot::
+    :include-source: true
+
+    import matplotlib.pyplot as plt
+    from matplotlib.collections import EllipseCollection
+    import numpy as np
+
+    rng = np.random.default_rng(0)
+
+    widths = (2, )
+    heights = (3, )
+    angles = (45, )
+    offsets = rng.random((10, 2)) * 10
+
+    fig, ax = plt.subplots()
+
+    ec = EllipseCollection(
+        widths=widths,
+        heights=heights,
+        angles=angles,
+        offsets=offsets,
+        units='x',
+        offset_transform=ax.transData,
+        )
+
+    ax.add_collection(ec)
+    ax.set_xlim(-2, 12)
+    ax.set_ylim(-2, 12)
+
+    new_widths = rng.random((10, 2)) * 2
+    new_heights = rng.random((10, 2)) * 3
+    new_angles = rng.random((10, 2)) * 180
+
+    ec.set(widths=new_widths, heights=new_heights, angles=new_angles)