[plt-scheme] nested vectors

On Feb 14, wooks wrote:
> working in Pretty Big
> 
> (define deposits (make-vector 17 (make-vector 17)))
> 
> Now I want to set the value of the index entry [0,11] in deposits to
> 39.
> 
> (vector-set! (vector-ref deposits 0) 11 39) gives a weird result.
> Please explain the result and correct me.

What you did is similar to

  (define deposits
    (let ([row (vector 1 2 3)])
      (vector row row row)))

but what you reaaly need is to have separate vectors for each row:

  (define deposits
    (vector (vector 1 2 3) (vector 1 2 3) (vector 1 2 3)))

You probably want something like

  (build-vector 17 (lambda (_) (make-vector 17)))

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          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
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