I have a question about JoinAcross
. In this case the left association is returned unchanged:
JoinAcross[{<|a -> 1, b -> X|>}, {<|a -> 2|>}, Key[a], "Left"]
(* {<|a -> 1, b -> X|>} *)
The result is expected. Notice that the "Left" is documented as allowing the first set (left) for which there is no matching right-side set. I was surprised to find that the following code return an empty list:
JoinAcross[{<|a -> 1, b -> X|>}, {}, Key[a], "Left"]
(* { } *)
Is this the expected behavior?
I now need to change my code so that if the right-side set is empty, then I need to insert a dummy association to prevent JoinAcross from deleting the whole thing.