let rec closeAreas db p distance =
    match db with
    | [] -> [p]
    | x::xs -> let a=List.hd p.shape.polygon b=List.hd x.shape.polygon in
                            if (dist a b <= distance)
                                then (x::closeAreas xs p distance)@closeAreas db x distance
                                else closeAreas xs p distance@closeAreas db x distance
    ;;

let rec diff set1 set2 =
    match set1 with
    | [] -> []
    | x::xs -> if belongs x set2
        then diff xs set2
        else x::(diff xs set2)
        ;;

let rec partRec db distance =
    match db with
    | [] -> [[]]
    | x::xs -> let close = closeAreas xs x d in
                            let set = diff xs close in
                                [close]@[partRec set distance]
    ;;
let partition db f = partRec db f;;