Given a list:
(setq mylist '("a1" "a2" "b1" "b2"))
How to delete all elements that match ^a?
What I want is "a1" and "a2" deleted, only left "b1" and "b2" in the list.
2 Answers
Do you want a new list that has only elements "b1" and "b2"? Or do you want the same list structure, but modified to have removed elements "a1" and "a2"?
@rpluim shows one way to do the former. A similar way to do the latter is to use cl-delete-if instead of cl-remove-if.
(setq mylist (cl-delete-if (lambda (k) (string-match-p "^a" k)) mylist)
(Make sure you set variable mylist to the result returned by cl-delete-if, if you expect that variable's value to reflect the deletion properly in all cases. See the Elisp manual, node Rearrangement for more about this.)
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My name has an
iin it, but single-character edits are not allowed. sigh– rpluimSep 18, 2018 at 7:47 -
There are many ways to do this, here's one:
(setq mylist (cl-remove-if (lambda (k)
(string-match "^a" k))
mylist)
^matches beginning-of-line, not beginning-of-string; see(elisp) Syntax of Regexpsfor how to do the latter, which is probably what you want here.alist(because there was none -- I honestly thought it was probably a contraction of "a list" which was written without knowledge of association lists). You've been adding them, though :) AFAICS the question isn't actually about alists.