CODEWITHSUNDEEP
functional-programmingracket
data_pi
data_pi

Reputation: 821

Racket - How to assign a length to a list

I was wondering, in racket, how would you assign a certain length to a list.

This is the code I want to run:

(check-expect (length a-list-of-length-104) 104)

How would you go about this without actually inputting 104 elements into the list?

This is my end goal:

(define (random-element a-list)
(list-ref a-list (random (length a-list))))

(random-element a-list-of-length-104)
(random-element a-list-of-length-104)
(random-element a-list-of-length-104)

It should produce a different output everytime.

Upvotes: 3

Views: 712

Answers (1)

Greg Hendershott
Greg Hendershott

Reputation: 16250

The length of a list is the number of elements it contains. So you can't "assign a length to a list".

However you can create a list with a certain number of elements, more conveniently. Assuming #lang racket, you can use build-list.

To build a list consisting of the integers from 0 through 103:

(build-list 104 values)

To build a list consisting of 104 of random real numbers:

(build-list 104 (lambda _ (random)))

Upvotes: 2

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