删除序言列表中的值和该值的所有重复项 [英] Remove both the value and all duplicates of that value in a list in prolog

问题描述

我在从序言列表中删除值时遇到一些麻烦. 我有一个颜色列表，我想为其添加颜色列表，并保留所有没有重复的值，然后删除其余的值.

I'm having some trouble removing values from a list in prolog. I have a list of colors and I want to add a list of colors to it and keep all the values that have no duplicate and remove the rest.

[green, red, blue, purple, yellow, brown, orange, black, purple]

所以紫色在此列表中出现了两次，我想将它们都删除. 这是我要返回的列表.

so purple appears twice in this list and I want to remove both of them. This is the list I want to be returned.

[green, red, blue, yellow, brown, orange, black]

我目前具有删除所有重复项的功能，但是我无法消除两种紫色.

I currently have this to remove all the duplicates but I can't get both purples out.

mymember(X,[H|_]) :- X==H,!.
mymember(X,[_|T]) :- mymember(X,T).

not(A) :- \+ call(A).

set([],[]).
set([Head|Tail],[Head|Out]) :-
    not(mymember(Head,Tail)),
    set(Tail, Out).
set([Head|Tail],Out) :-
    mymember(Head,Tail),
    set(Tail, Out).

这是我现在得到的结果:

this is the result I get now:

[green, red, blue, yellow, brown, orange, black, purple]

推荐答案

简单方法...单线:

singletons(Xs,Zs) :-
  findall( X , ( append(P,[X|S],Xs), \+member(X,P), \+member(X,S) ) , Zs )
  .

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