筛选列表中的值

筛选列表中的值

// 取出 [[("XX",1);("XX",2)];[...]] 中的 XX// [["XX";"XX"];[...]] let t1 = [[("XX",1);("XX",2)]]t1 |> List.map (List.map (fun (a, b) -> a)) // [["XX"; "XX"]]
let t2 = [[("AA",1);("BB",2)];["CC",3];["DD",4]]
let check2 ( i:'a) fz = let t = List.fold (fun acc (_,x) -> acc+x) 0 i if ( t = fz ) then true else false
t2 |> List.filter (fun i -> check2 i 3) |> List.map (List.map (fun (a, _) -> a))// [["AA"; "BB"]; ["CC"]]