How to remove multiple items from a list?

Question

Hi,

I have a list [2 3 5] which I want to use to remove items from another list like [1 2 3 4 5], so that I get [1 4].

thanks

Answer 1

Loop through your larger list. For each item in that list compare it to the values in the list you would like to remove. If you find a match remove that item from your orginal list. When complete you would get what you are looking for.

Answer 2

user=> (use 'clojure.set)
nil
user=> (difference (set [1 2 3 4 5]) (set [2 3 5]))
#{1 4}

Reference:

• http://clojure.org/data%5Fstructures#toc22
• http://clojure.org/api#difference

Answer 3

Try this:

(let [a [1 2 3 4 5]
      b [2 3 5]]
  (remove (set b) a))

which returns (1 4).

The remove function, by the way, takes a predicate and a collection, and returns a sequence of the elements that don't satisfy the predicate (a set, in this example).