Add a comment about _transforms

jkseppan · jkseppan · commit 123deb5b3f95 · 2015-10-01T20:31:22.000+03:00
diff --git a/lib/matplotlib/collections.py b/lib/matplotlib/collections.py
@@ -80,6 +80,12 @@ class Collection(artist.Artist, cm.ScalarMappable):
     # _offsets must be a Nx2 array!
     _offsets.shape = (0, 2)
     _transOffset = transforms.IdentityTransform()
+    #: Either a list of 3x3 arrays or an Nx3x3 array of transforms, suitable
+    #: for the `all_transforms` argument to
+    #: :meth:`~matplotlib.backend_bases.RendererBase.draw_path_collection`;
+    #: each 3x3 array is used to initialize an
+    #: :class:`~matplotlib.transforms.Affine2D` object.
+    #: Each kind of collection defines this based on its arguments.
     _transforms = np.empty((0, 3, 3))
 
     def __init__(self,
