From: Oleh Krehel <ohwoeowho@gmail.com>
To: Nicolas Petton <nicolas@petton.fr>
Cc: Stefan Monnier <monnier@iro.umontreal.ca>,
emacs-devel <emacs-devel@gnu.org>
Subject: Re: Would seq-range and seq-mapcat be useful?
Date: Fri, 30 Jan 2015 16:38:24 +0100 [thread overview]
Message-ID: <CAA01p3quKTexwMSBS-Umb10gVMF6LW7YuXR3erUjBCPC1pjeSA@mail.gmail.com> (raw)
In-Reply-To: <87lhkkefhn.fsf@petton.fr>
On Fri, Jan 30, 2015 at 11:21 AM, Nicolas Petton <nicolas@petton.fr> wrote:
>
> Oleh Krehel <ohwoeowho@gmail.com> writes:
>
>> Hi Nicolas,
>>
>> On Thu, Jan 29, 2015 at 11:06 PM, Nicolas Petton <nicolas@petton.fr> wrote:
>>
>>> Sure, `seq-range' would be a convenient way to create a sequence of
>>> numbers. A simple implementation could be:
>>>
>>> (defun seq-range (start end)
>>> (let ((lst nil))
>>> (while (< start end)
>>> (push end lst)
>>> (setq end (1- end)))
>>> lst))
>>
>> This is just `number-sequence' from subr.el.
>
> Indeed :)
>
> Nico
> --
> Nicolas Petton
> http://nicolas-petton.fr
>
I'd like to have this:
(defun seq-group-by (fn lst)
(nreverse
(cl-reduce
(lambda (acc it)
(let* ((key (funcall fn it))
(cell (assoc key acc)))
(if cell
(setcdr cell (push it (cdr cell)))
(push (list key it) acc))
acc))
lst
:initial-value nil)))
(seq-group-by
#'car
'(("a" 1)
("b" 2)
("b" 5)
("c" 1)))
;; (("a" ("a" 1))
;; ("b" ("b" 5)
;; ("b" 2))
;; ("c" ("c" 1)))
(seq-group-by
#'cadr
'(("a" 1)
("b" 2)
("b" 5)
("c" 1)))
;; ((1 ("c" 1)
;; ("a" 1))
;; (2 ("b" 2))
;; (5 ("b" 5)))
Is this already somewhere?
Oleh
next prev parent reply other threads:[~2015-01-30 15:38 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-29 16:54 Would seq-range and seq-mapcat be useful? Nicolas Petton
2015-01-29 18:02 ` Artur Malabarba
2015-01-29 22:03 ` Nicolas Petton
2015-01-29 21:40 ` Stefan Monnier
2015-01-29 22:06 ` Nicolas Petton
2015-01-30 6:09 ` Stefan Monnier
2015-01-30 8:00 ` Oleh Krehel
2015-01-30 10:21 ` Nicolas Petton
2015-01-30 15:38 ` Oleh Krehel [this message]
2015-01-30 15:59 ` Nicolas Richard
2015-01-30 16:04 ` Oleh Krehel
2015-01-30 16:05 ` Oleh Krehel
2015-01-30 16:36 ` Nicolas Richard
2015-01-30 16:51 ` Oleh Krehel
2015-01-30 16:23 ` Nicolas Petton
2015-02-02 0:11 ` Nicolas Petton
2015-02-02 7:49 ` Oleh Krehel
2015-02-02 9:28 ` Nicolas Petton
2015-02-02 18:34 ` Mark Oteiza
2015-02-02 18:39 ` Oleh Krehel
2015-02-04 12:02 ` Ted Zlatanov
2015-01-30 8:20 ` What about seq-slice? (Was: Would seq-range and seq-mapcat be useful?) Mark Oteiza
2015-01-30 10:25 ` Nicolas Petton
2015-01-30 11:09 ` seq-thread-first/last (was: What about seq-slice?) Michael Heerdegen
2015-01-30 11:59 ` Nicolas Petton
2015-01-30 12:08 ` seq-thread-first/last Michael Heerdegen
2015-01-30 12:21 ` seq-thread-first/last Nicolas Petton
2015-01-30 12:17 ` seq-thread-first/last David Kastrup
2015-01-30 12:25 ` seq-thread-first/last Nicolas Petton
2015-01-30 12:33 ` seq-thread-first/last Michael Heerdegen
2015-01-30 12:58 ` seq-thread-first/last Bozhidar Batsov
2015-01-30 14:02 ` seq-thread-first/last Artur Malabarba
2015-01-30 14:15 ` seq-thread-first/last Michael Heerdegen
2015-01-30 17:17 ` What about seq-slice? Mark Oteiza
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