How to remove several items from a unsorted list in Netlogo

问题

so i'm a bit struggling with Lists in Netlogo, so basically i've two lists and i want to remove the items that are in List 1 from List 2, for example:

List 1 : [8 6 9 7 1 3]

List 2: [5 9 8]

Resulting List : [6 7 1 3]

I've tried the following code but it returns an empty list:

if List 2 != []
   [ 
          foreach List 2 
          [
             let p position ? List 1 
             if p = true
                [
                  set List 1 remove-item p List 1
                ]
          ]
    ]

Any ideas ?

回答1:

A combination of member? and filter will get you there:

let list1 [8 6 9 7 1 3]
let list2 [5 9 8]
let result filter [ x -> not member? x list2 ] list1
print result

Will print the desired:

[6 7 1 3]

Tip: whenever you find yourself trying to use an index for anything in NetLogo, you are probably not doing things in the optimal way. NetLogo has tons of functions (like filter, in this case) that operate on lists as a whole. There is rarely a need to explicitly loop through them.

来源：https://stackoverflow.com/questions/49379498/how-to-remove-several-items-from-a-unsorted-list-in-netlogo