On 2024-07-22, B. Pym <
Nobody447095@here-nor-there.org> wrote:
(defun distribution1 (items values test)
(let ((table (make-hash-table :test test)))
(loop for item in items
for value in values
do (incf (gethash item table 0) value))
(let ((items-list nil))
(maphash (lambda (item sum-value)
(push (cons item sum-value) items-list))
table)
(sort items-list #'> :key #'cdr))))
An example call:
CL-USER 58 > (distribution1 '("a" "b" "c" "b" "a" "f" "e" "g"
"h" "k" "z" "k" "r" "u" "f")
'(1 5 8 7 14 8 3 7 9 4 3 21 5 7 9)
#'equal)
(("k" . 25) ("f" . 17) ("a" . 15) ("b" . 12) ("h" . 9) ("c" . 8)
("g" . 7) ("u" . 7) ("r" . 5) ("e" . 3) ("z" . 3))
Gauche Scheme
(define (distribution1 items values test)
(let1 table (make-hash-table test)
(for-each
(^(item value)
(hash-table-update! table item (cut + value <>) 0))
items
values)
(sort (hash-table->alist table) > cdr)))
(distribution1 '("a" "b" "c" "b" "a" "f" "e" "g"
"h" "k" "z" "k" "r" "u" "f")
'(1 5 8 7 14 8 3 7 9 4 3 21 5 7 9)
'equal?)
(("k" . 25) ("f" . 17) ("a" . 15) ("b" . 12) ("h" . 9) ("c" . 8) ("g" . 7)
("u" . 7) ("r" . 5) ("z" . 3) ("e" . 3))
This is the TXR Lisp interactive listener of TXR 294.
Quit with :quit or Ctrl-D on an empty line. Ctrl-X ? for cheatsheet.
I'm not addicted to procrastination. I can start any time I want to!
(defun distrib (items values)
(let ((h (hash)))
(each ((i items) (v values))
(inc [h i 0] v))
[sort (hash-alist h) : car]))
distrib
(distrib '("a" "b" "c" "b" "a" "f" "e" "g"
"h" "k" "z" "k" "r" "u" "f")
'(1 5 8 7 14 8 3 7 9 4 3 21 5 7 9))
(("a" . 15) ("b" . 12) ("c" . 8) ("e" . 3) ("f" . 17) ("g" . 7)
("h" . 9) ("k" . 25) ("r" . 5) ("u" . 7) ("z" . 3))
Look how much the better code looks when you don't have silly
things like a for-each that takes a lambda, and having to
call a function with a functional argument to update a hash
cell.
Also, when you make equal hash tables default, most of the time
it's the right default. You can skip the test arguments and whatnot.
Names like "hash-table->alist" make my eyes bleed.
Oops, I sorted on the wrong thing.
(defun distrib (items values)
(let ((h (hash)))
(each ((i items) (v values))
(inc [h i 0] v))
[sort (hash-alist h) > cdr]))
distrib
(distrib '("a" "b" "c" "b" "a" "f" "e" "g"
"h" "k" "z" "k" "r" "u" "f")
'(1 5 8 7 14 8 3 7 9 4 3 21 5 7 9))
(("k" . 25) ("f" . 17) ("a" . 15) ("b" . 12) ("h" . 9) ("c" . 8)
("u" . 7) ("g" . 7) ("r" . 5) ("z" . 3) ("e" . 3))
Using group-reduce:
(defun distrib (items values)
(flow [group-reduce (hash) car [mapf + use cdr]
[mapcar cons items values] 0]
hash-alist
(sort @1 > cdr)))
distrib
(distrib '("a" "b" "c" "b" "a" "f" "e" "g"
"h" "k" "z" "k" "r" "u" "f")
'(1 5 8 7 14 8 3 7 9 4 3 21 5 7 9))
(("k" . 25) ("f" . 17) ("a" . 15) ("b" . 12) ("h" . 9) ("c" . 8)
("u" . 7) ("g" . 7) ("r" . 5) ("z" . 3) ("e" . 3))
Using group-reduce on the keys, using pop to get the values,
so we don't cons up list of pairs up-front:
(defun distrib (items values)
(flow [group-reduce (hash) identity [mapf + use (ret (pop values))]
items 0]
hash-alist
(sort @1 > cdr)))
distrib
(distrib '("a" "b" "c" "b" "a" "f" "e" "g"
"h" "k" "z" "k" "r" "u" "f")
'(1 5 8 7 14 8 3 7 9 4 3 21 5 7 9))
(("k" . 25) ("f" . 17) ("a" . 15) ("b" . 12) ("h" . 9) ("c" . 8)
("u" . 7) ("g" . 7) ("r" . 5) ("z" . 3) ("e" . 3))
--
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