vl-sort (AutoLISP)

Sorts the elements in a list according to a given compare function

Supported Platforms: Windows and Mac OS

Signature

(vl-sort lst comparison-function)

lst

Type: List

Any list to sort.

comparison-function

Type: Subroutine or Symbol

A comparison function. This can be any function that accepts two arguments and returns T (or any non-nil value) if the first argument precedes the second in the sort order. The comparison-function value can take one of the following forms:

• A symbol (function name)
• '(LAMBDA (A1 A2) ...)
• (FUNCTION (LAMBDA (A1 A2) ...))

Return Values

Type: List

A list containing the elements of lst in the order specified by comparison-function. Duplicate elements may be eliminated from the list.

Examples

Sort a list of numbers:

(vl-sort '(3 2 1 3) '<)
(1 2 3)

Note that the result list contains only one 3.

Sort a list of 2D points by Y coordinate:

(vl-sort '((1 3) (2 2) (3 1))
             (function (lambda (e1 e2)
                         (< (cadr e1) (cadr e2)))))
((3 1) (2 2) (1 3))

Sort a list of symbols:

(vl-sort
   '(a d c b a)
   '(lambda (s1 s2)
    (< (vl-symbol-name s1) (vl-symbol-name s2))))
(A B C D)       ;  Note that only one A remains in the result list