Elisp: Remove Elements in List

Remove by Equality Test, on a List of Symbols or Integers

these functions work only if your list items are all symbol or integer.

remq

(remq x list)

• Remove all x in list.
• Returns a new list.
• The original list is unchanged.
• Comparison is done with eq. [see Elisp: Equality Test]

(setq xx '(3 4 5))
(remq 4 xx) ; (3 5)
xx ; (3 4 5)

delq

(delq x list)

• Remove all x in list.
• The original list is destroyed.
• Returns a new list.
• Comparison is done with eq. [see Elisp: Equality Test]

(setq xx '(3 4 5))

;; always set result to the same var
(setq xx (delq 4 xx)) ; (3 5)

Delete Duplicates

delete-dups

(delete-dups list)

• Remove duplicates, return a new list.
• Original list is destroyed.
• Comparison done using equal. [see Elisp: Equality Test]

(let (xx)
  (setq xx '(3 4 5 3 2))
  (setq xx (delete-dups xx)))
  ;; (3 4 5 2)