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From: "B. Pym" <Nobody447095@here-nor-there.org>
Newsgroups: comp.lang.python,comp.lang.lisp
Subject: Re: How do i get multiple Min() values?
Date: Sat, 13 Jul 2024 19:11:07 -0000 (UTC)
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B. Pym wrote:

> HenHanna wrote:
> 
> > 
> > How do i get multiple Min() values?
> > 
> >           e.g.      for   Y = (x-2)*(x-3)   for x in range(-10,10)
> >                                    the min Y is hit twice
> > 
> > 
> > print(  min( ((x-2)*(x-3),  (x, (x-2, x-3)))
> >                                            for x in range(-10,10) ) )
> > 
> > 
> > 
> > is this easy in Scheme(Gauche) ?
> 
> Gauche Scheme
> 
> (use gauche.collection) ;; fold2
> 
> (define (min-by fn lst)
>   (if (null? lst)
>     (values '() #f)
>     (fold2
>       (lambda (x best worth)
>         (let ((score (fn x)))
>           (cond ((< score worth) (values (list x) score))
>                 ((= score worth) (values (cons x best) worth))
>                 (#t (values best worth)))))
>       (take lst 1) (fn (car lst))
>       (cdr lst))))
> 
> (min-by (lambda(x) (* (- x 2) (- x 3))) (lrange -10 11))
> 
>   ===>
> (3 2)
> 0
>  

(use gauche.collection) ;; fold2

(define (min-max-by fn lst)
  (define (use  compare x score best worth)
    (cond ((compare score worth) (list (list x) score))
          ((= score worth) (list (cons x best) worth))
          (#t (list best worth))))
  (if (null? lst)
    (values (list '() #f) (list '() #f))
    (let ((initial (list (take lst 1) (fn (car lst)))))
      (fold2
        (lambda (x mini maxi)
          (let ((score (fn x)))
            (values
              (apply use < x score mini) 
              (apply use > x score maxi))))
        initial initial
        (cdr lst)))))

(min-max-by (lambda(x) (* (- x 2) (- x 3))) (lrange -10 11))

  ===>
((3 2) 0)
((-10) 156)