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comp / comp.lang.lisp / Re: A simple Lisp program -- algorithm and speed issues

SubjectAuthor
* Re: A simple Lisp program -- algorithm and speed issuesB. Pym
`- Re: A simple Lisp program -- algorithm and speed issuesKaz Kylheku

1
Subject: Re: A simple Lisp program -- algorithm and speed issues
From: B. Pym
Newsgroups: comp.lang.lisp, comp.lang.scheme
Organization: A noiseless patient Spider
Date: Fri, 20 Sep 2024 06:44 UTC
Path: eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Nobody447095@here-nor-there.org (B. Pym)
Newsgroups: comp.lang.lisp,comp.lang.scheme
Subject: Re: A simple Lisp program -- algorithm and speed issues
Date: Fri, 20 Sep 2024 06:44:24 -0000 (UTC)
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Hrvoje Niksic wrote:

> Here is an interesting, not entirely academic problem that me and a
> colleague are "wrestling" with. Say there is a file, containing
> entries like this:
>
> foo 5
> bar 20
> baz 4
> foo 6
> foobar 23
> foobar 3
> ...
>
> There are a lot of lines in the file (~10000), but many of the words
> repeat (there are ~500 unique words). We have endeavored to write a
> program that would sum the occurences of each word, and display them

I think he means: sum the numbers associated with the words.

> sorted alphabetically, e.g.:
>
> bar 20
> baz 4
> foo 11
> foobar 26
> ...

The file contains:

foo 5
bar 20
baz 4
foo 6
foobar 23
foobar 3
bar 68
baz 33

Gauche Scheme

(define (process file)
(let1 result '()
(with-input-from-file file
(cut generator-for-each
(lambda (item)
(ainc! result (symbol->string item) (read)))
read))
(sort result string<? car)))

(process "output.dat")
===>
(("bar" . 88) ("baz" . 37) ("foo" . 11) ("foobar" . 26))

Given:

(define-syntax ainc!
(syntax-rules ()
[(_ alist key val func default)
(let ((pair (assoc key alist)))
(if pair
(set-cdr! pair (func val (cdr pair)))
(set! alist (cons (cons key (func val default)) alist))))]
[(_ alist key val func)
(ainc! alist key val func 0)]
[(_ alist key val)
(ainc! alist key val +)]
[(_ alist key)
(ainc! alist key 1)]))

Subject: Re: A simple Lisp program -- algorithm and speed issues
From: Kaz Kylheku
Newsgroups: comp.lang.lisp, comp.lang.scheme
Organization: A noiseless patient Spider
Date: Fri, 20 Sep 2024 21:28 UTC
References: 1
Path: eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: 643-408-1753@kylheku.com (Kaz Kylheku)
Newsgroups: comp.lang.lisp,comp.lang.scheme
Subject: Re: A simple Lisp program -- algorithm and speed issues
Date: Fri, 20 Sep 2024 21:28:29 -0000 (UTC)
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On 2024-09-20, B. Pym <Nobody447095@here-nor-there.org> wrote:
> The file contains:
>
> foo 5
> bar 20
> baz 4
> foo 6
> foobar 23
> foobar 3
> bar 68
> baz 33
>
> Gauche Scheme

Given: 13 more lines of macro cruft, half of which
simulates optional arguments with default values.

> (define (process file)
> (let1 result '()
> (with-input-from-file file
> (cut generator-for-each
> (lambda (item)
> (ainc! result (symbol->string item) (read)))
> read))
> (sort result string<? car)))
>
> (process "output.dat")
> ===>
> (("bar" . 88) ("baz" . 37) ("foo" . 11) ("foobar" . 26))

TXR Lisp:

1> (flow "file"
file-get-objects
(tuples 2)
(group-map [chain car symbol-name] (op sum @1 cadr))
hash-alist
(sort @1 : car))
(("bar" . 88) ("baz" . 37) ("foo" . 11) ("foobar" . 26))

Given:

Vanilla installation of TXR.

--
TXR Programming Language: http://nongnu.org/txr
Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal
Mastodon: @Kazinator@mstdn.ca

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