sorting a list of lists in lisp

Question

I have a list of lists of this form :

testlist((a 22) ( b 2) ( c 5))

My goal is to sort the testlist based on the numbers' values (5 first greatest values). Is there a way to achieve this without having to iterate over the list and compare numbers to each other?

Kaz · Accepted Answer · 2016-09-28 02:19:03Z

5

In ANSI Common Lisp:

(sort (copy-list '((a 22) (b 2) (c 5)))  #'< :key #'second)
-> ((B 2) (C 5) (A 22))

The copy-list is there because sort clobbers the input list. We need that because our input list is a literal, but even if it isn't, sometimes you don't want to scramble the original object that you wish to sort.

answered Sep 28, 2016 at 2:19

Kaz

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