You might want your encoding-scheme to be a function,
and you want to evaluate that function inside generate-chromosome:
(define (generate-chromosome encoding-scheme number-of-genes)
(cond [(zero? number-of-genes) empty]
[else (cons (encoding-scheme)
(generate-chromosome encoding-scheme (sub1
number-of-genes)))]))
(define (binary-encoding-scheme)
(random 2))
(define (value-encoding-scheme)
(random))
(generate-chromosome binary-encoding-scheme 10)
(generate-chromosome value-encoding-scheme 10)
(0 1 1 1 1 1 0 1 1 0)
(0.17586764776624525
0.13437314563189037
0.585523111696543
0.6533766686688987
0.09071850144989983
0.8804515074319006
0.6998388642832832
0.599233672637633
0.5238661544779689
0.72734166222789)
>
rac
On Dec 19, 2013, at 7:42 PM, Rian Shams wrote:
> Hello All,
>
> I am new to Racket and just started building an evolutionary computing module
> to supplement my research and learn more about Racket.
>
> When it comes to representing a chromosome, there are many encoding schemes
> one can choose from. To start I would like to build a function that lets the
> user choose the encoding scheme they would like by being able to directly
> insert it into the function call. So far I have created this:
>
> (define (generate-chromosome encoding-scheme number-of-genes)
> (cond [(zero? number-of-genes) empty]
> [else (cons encoding-scheme
> (generate-chromosome encoding-scheme (sub1
> number-of-genes)))]))
>
> Two popular encoding schemes are the binary encoding scheme and the real
> value encoding scheme:
>
> (define binary-encoding-scheme
> (random 2))
> (define value-encoding-scheme
> (random))
>
> So then calling this function using the binary encoding scheme:
>
> (generate-chromosome binary-encoding-scheme 10)
>
> gives either a list of only ten 1's or a list of only ten 0's. Random only
> works once and whatever the first random value is stays and doesn't change.
>
> How would I make random re-evaluate each time given that I want it to be
> included in the definition of an encoding scheme?
>
> As an alternate, the function below works when I directly include (random 2)
> in for a value in the encoding scheme, but I prefer the structure of the
> above function.
>
> (define (generate-chromosome-2 number-of-genes)
> (cond [(zero? number-of-genes) empty]
> [else (cons (random 2) ;binary-encoding-scheme
> (generate-chromosome-2 (sub1 number-of-genes)))]))
>
> So the function call
> (generate-chromosome-2 10) gives the desired result, but doesn't fit the
> needed structure.
>
> Any help would be much appreciated.
>
> Best Regards,
> --
> Rian Shams
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