Merge
Merge[{assoc1, assoc2, ...}, f] merges associations, using f to combine values with the same key.
Examples
Merge associations with conflict resolution:
a1 = <|"x" -> 1, "y" -> 2|>
a2 = <|"y" -> 3, "z" -> 4|>
(* Sum values with same key *)
Merge[{a1, a2}, Total]
(* <|"x" -> 1, "y" -> 5, "z" -> 4|> *)
(* Keep first value *)
Merge[{a1, a2}, First]
(* <|"x" -> 1, "y" -> 2, "z" -> 4|> *)Please visit the official Wolfram Language Reference for more details.