From: Slobodan Blazeski
Subject: How to loop over multi-dimesional array
Date: Mon, 01 Jun 2009 08:09:24 +0000
Message-ID: <9ba9ff37-b196-4604-a03e-4aec1f8226bf@e21g2000yqb.googlegroups.com>

I have some multi-dimensional array (not a vector) how to setf its
elements  one by one?
For example setting 2 dimensional culd be done with below, but what if
number of axis is not know until runtime?

1 >(setq arr  (make-array '(2 3)))
#2A((NIL NIL NIL) (NIL NIL NIL))

2 > (dotimes (I1 2)
           (dotimes (i2 3)
             (setf (aref arr i1 i2) (random 10))))
NIL

3 > arr
#2A((8 5 4) (4 3 8))

• Re: How to loop over multi-dimesional array John Thingstad
  • Re: How to loop over multi-dimesional array Slobodan Blazeski

From: John Thingstad
Subject: Re: How to loop over multi-dimesional array
Date: Mon, 01 Jun 2009 08:52:07 +0000
Message-ID: <op.uut785kvut4oq5@pandora>

På Mon, 01 Jun 2009 10:09:24 +0200, skrev Slobodan Blazeski  
<·················@gmail.com>:

> I have some multi-dimensional array (not a vector) how to setf its
> elements  one by one?
> For example setting 2 dimensional culd be done with below, but what if
> number of axis is not know until runtime?
>
> 1 >(setq arr  (make-array '(2 3)))
> #2A((NIL NIL NIL) (NIL NIL NIL))
>
> 2 > (dotimes (I1 2)
>            (dotimes (i2 3)
>              (setf (aref arr i1 i2) (random 10))))
> NIL
>
> 3 > arr
> #2A((8 5 4) (4 3 8))

look up row-major-aref and array-total-size

(dotimes (i (array-total-size array))
   (setf (row-major-aref array i) (random 10)))

Otherwise array-dimensions gives the dimensions as a list so:

(loop for j = 0 then (incf j)
       for size in (array-dimensions array)
	do (dotimes (i size) (setf (aref array j i) (random 10)))

or something like that.

---------------------
John Thingstad

From: Slobodan Blazeski
Subject: Re: How to loop over multi-dimesional array
Date: Mon, 01 Jun 2009 08:59:47 +0000
Message-ID: <1729727b-d97b-488f-b71d-ac5e42c025fc@g19g2000yql.googlegroups.com>

On Jun 1, 10:52 am, "John Thingstad" <·······@online.no> wrote:
> På Mon, 01 Jun 2009 10:09:24 +0200, skrev Slobodan Blazeski  
> <·················@gmail.com>:
>
> > I have some multi-dimensional array (not a vector) how to setf its
> > elements  one by one?
> > For example setting 2 dimensional culd be done with below, but what if
> > number of axis is not know until runtime?
>
> > 1 >(setq arr  (make-array '(2 3)))
> > #2A((NIL NIL NIL) (NIL NIL NIL))
>
> > 2 > (dotimes (I1 2)
> >            (dotimes (i2 3)
> >              (setf (aref arr i1 i2) (random 10))))
> > NIL
>
> > 3 > arr
> > #2A((8 5 4) (4 3 8))
>
> look up row-major-aref
Row-major-aref is just what I needed many thanks.
cheers
bobi

>and array-total-size
>
> (dotimes (i (array-total-size array))
>    (setf (row-major-aref array i) (random 10)))
>
> Otherwise array-dimensions gives the dimensions as a list so:
>
> (loop for j = 0 then (incf j)
>        for size in (array-dimensions array)
>         do (dotimes (i size) (setf (aref array j i) (random 10)))
>
> or something like that.
>
> ---------------------
> John Thingstad