vector-pop and vector-remove

[mazert]

Hello,

I have two functions I often use to remove an element from a vector, and
it will be nice to add it directly in the vector module, or in the worst
case into a specific package. Cause I'm sure it will be useful and we
already have such functions for list, but not for vector...

; Remove the ith element of vector v
(define (vector-pop i v)
(vector-append (vector-copy v 0 i) (vector-copy v (+ i 1))))

; Like remove (from list) but for a vector
(define (vector-remove ele v)
(vector-filter-not (λ (x) (equal? x ele)) v))


Of course we have to use the check-vector/index to raise an error if "i"
is out of range (see vector.rkt).

[Jens Axel Søgaard]

Hi,

For programs that need to use "vectors whose length can change"

grow vectors are often the right choice:

http://docs.racket-lang.org/data/gvector.html

/Jens Axel

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Jens Axel Søgaard

[mazert]

Le 02/08/2015 13:04, Jens Axel Søgaard a écrit :
> Hi,
>
> For programs that need to use "vectors whose length can change"
> grow vectors are often the right choice:
>
> http://docs.racket-lang.org/data/gvector.html

Ok, I didn't know about this data structure, and effectively you are
right : the performance are better. I tested with a simple program
computing time to remove the first element from a gvector and a vector,
both contains 1000000 elements :

gvector : 7 ms
vector : 102 ms

So that was a very bad idea, thank you for letting me know :)

[Jens Axel Søgaard]

Hi,

From: http://stackoverflow.com/a/27589146/23567

Here is how I choose which data structure to use in Racket:

DATA STRUCTURE   ACCESS       NUMBER     INDICES
List:            sequential   Variable   not used
Struct:          random       Fixed      names
Vector:          random       Fixed      integer
Growable vector: random       Variable   integer
Hash:            random       Variable   hashable
Splay:           random       Variable   non-integer, total order

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