Performance notes for interleave_longest and roundrobin

more_itertools/more.py

@@ -801,6 +801,10 @@ def interleave_longest(*iterables):
         >>> list(interleave_longest([1, 2, 3], [4, 5], [6, 7, 8]))
         [1, 4, 6, 2, 5, 7, 3, 8]
 
+    This function produces the same output as :func:`roundrobin`, but may
+    perform better for some inputs (in particular when the number of iterables
+    is large).
+
     """
     i = chain.from_iterable(zip_longest(*iterables, fillvalue=_marker))
     return (x for x in i if x is not _marker)

more_itertools/recipes.py

@@ -300,7 +300,9 @@ def roundrobin(*iterables):
         >>> list(roundrobin('ABC', 'D', 'EF'))
         ['A', 'D', 'E', 'B', 'F', 'C']
 
-    See :func:`interleave_longest` for a slightly faster implementation.
+    This function produces the same output as :func:`interleave_longest`, but
+    may perform better for some inputs (in particular when the number of
+    iterables is small).
 
     """
     # Recipe credited to George Sakkis