Merge pull request matplotlib#15841 from tacaswell/doc_set_offsets

DOC: specify the expected shape in the Collection.set_offset

Author: timhoffm

lib/matplotlib/collections.py

@@ -475,7 +475,7 @@ def set_offsets(self, offsets):
 
         Parameters
         ----------
-        offsets : float or sequence of floats
+        offsets : array-like (N, 2) or (2,)
         """
         offsets = np.asanyarray(offsets, float)
         if offsets.shape == (2,):  # Broadcast (2,) -> (1, 2) but nothing else.