## Coerce bidimensional array into list

Discussion of Common Lisp

### Coerce bidimensional array into list

I know I can use the coerce function to make a list from a given array, However, when I give it a multidimensional array I get a list of all elements.

Is there any "easy way" to get ((1 2) (3 4)) from #((1 2) (3 4))?

Thanks in advance. Ferreira

Posts: 5
Joined: Thu Apr 02, 2009 5:07 am

### Re: Coerce bidimensional array into list

Ferreira wrote:Is there any "easy way" to get ((1 2) (3 4)) from #((1 2) (3 4))?

Actually, #((1 2) (3 4)) is a vector of two elements, both of which are lists, so you can:

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`> #((1 2)(3 4))#((1 2) (3 4))> (coerce #((1 2)(3 4)) 'list)((1 2) (3 4))`

Real two dimensional arrays (with read syntax like #2A((1 2)(3 4)) ) are not sequences, and so as far as I know there is no built in way to transform them into nested list. But it is easy enough with a simple nested loop, like for example:

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`(defun to-list (2d-array)  (loop for i from 0 below (array-dimension 2d-array 0)        collect (loop for j from 0 below (array-dimension 2d-array 1)                      collect (aref 2d-array i j))))CL-USER> (to-list #2A((1 2)(3 4)))((1 2) (3 4))`
ramarren

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Joined: Sun Jun 29, 2008 4:02 am
Location: Warsaw, Poland

### Re: Coerce bidimensional array into list

Ferreira wrote:I know I can use the coerce function to make a list from a given array, However, when I give it a multidimensional array I get a list of all elements.

Is there any "easy way" to get ((1 2) (3 4)) from #((1 2) (3 4))?

Thanks in advance. You can use :initial-contents keyword argument for make-array:
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`(make-array '(2 2) :initial-contents '((1 2) (3 4)))=>#2A((1 2) (3 4))`
dmitry_vk

Posts: 96
Joined: Sat Jun 28, 2008 8:01 am
Location: Russia, Kazan 