another stats problem, example solution [stats.el]

another stats problem, example solution [stats.el]

[Emanuel Berg]

Problem:

Return a list of N random numbers.
Every number is at least MIN.
The sum of the numbers is SUM.

Suggested solution, linear to SUM.

;;; -*- lexical-binding: t -*-
;;
;; this file:
;;   https://dataswamp.org/~incal/emacs-init/stats.el

(require 'cl-lib)

(defun random-distribution (n min sum)
  "Return a list of N random numbers.
Every number is at least MIN.
The sum of the numbers is SUM."
  (let ((min-share (* n min)))
    (unless (<= min-share sum)
      (error "Bogus indata, unsolvable") )
    (let ((vals (make-list n min))
          (pool (- sum min-share)) )
      (cl-loop while (and (< 0 pool)
                          (cl-decf pool) )
               do (cl-incf (nth (random n) vals)) )
      vals) ))

(defalias 'rd #'random-distribution)

;; (apply #'+ (rd 10 3 100)) ; 100
;;
;; (rd 10 10 100) ; border case check, but OK
;;
;; (rd 10 20 100) ; Bogus indata, unsolvable
;;
;; example distributions for n = 10, min = 3, and sum = 100:
;;   (12  8  8 10  7  6 19  9  7 14)
;;   ( 8 12  7 12  9 10  9  9 12 12)
;;   (14  6 15 11  9  9  6  8 11 11)
;;   ( 8 12  7  9 10  9 10 13 10 12)
;;   (12 12 15  6 10  8  6 10 14  7)
;;   ( 9  7 10  8 11 10  9 10 13 13)
;;   ( 7 13 13 10 13 10  5 13  5 11)
;;   (13  8  6  9 13  8 11  7 10 15)
;;   ( 7 10  5  6 17 14  8 10 14  9)
;;   (11 10  8  9 11 10 14 11  8  8)

(provide 'stats)

-- 
underground experts united
https://dataswamp.org/~incal

Re: another stats problem, example solution [stats.el]

[John Haman]

Seems neither statistical (having to do with inferring something about a population from a sample) or topical.

-- 
Dr. John Haman
Maryland, USA

Re: another stats problem, example solution [stats.el]

[Emanuel Berg]

John Haman wrote:

> Seems neither statistical (having to do with inferring
> something about a population from a sample) or topical.

`1-'

-- 
underground experts united
https://dataswamp.org/~incal

Re: another stats problem, example solution [stats.el]

[Philip Kaludercic]

Emanuel Berg <incal@dataswamp.org> writes:

> John Haman wrote:
>
>> Seems neither statistical (having to do with inferring
>> something about a population from a sample) or topical.
>
> `1-'

What I believe that John is trying to say is that the development
mailing list seems to be the wrong place to share your script, unless
you are proposing to add something specific to Emacs?

Re: another stats problem, example solution [stats.el]

[Emanuel Berg]

Philip Kaludercic wrote:

> What I believe that John is trying to say is that the
> development mailing list seems to be the wrong place to
> share your script

`1-'

-- 
underground experts united
https://dataswamp.org/~incal