KeySelect

KeySelect[assoc, crit] selects elements in the association assoc for which crit applied to their keys is True.

KeySelect[crit] represents an operator form of KeySelect that can be applied to an expression.

Examples

Select keys matching criterion:

KeySelect[<|1 -> "a", 2 -> "b", 3 -> "c"|>, OddQ]
(* <|1 -> "a", 3 -> "c"|> *)

Select string keys:

KeySelect[<|"x" -> 1, "y" -> 2, "z" -> 3|>, StringMatchQ[#, "x" | "z"] &]
(* <|"x" -> 1, "z" -> 3|> *)

Please visit the official Wolfram Language Reference for more details.