Re: [Pdl-porters] SDL::Surface::new_from and PLot question

David Mertens wrote:
> On Mon, Nov 16, 2009 at 4:51 PM, Kartik Thakore 
> <[email protected] <mailto:[email protected]>> wrote:
> 
>     How do I update this?  like animation?
> 
>     while(1)
>     {
> 
>       $pdl_memory->get_dataref();
> 
>     }
> 
> 
> Yeah, you know, I used a terrible variable name for that piddle.  Let's 
> try this:
>  
> --------%<--------
> 
> use PDL;
> use PDL::NiceSlice;
> 
> # Allocate a 10x10 array for rgb.  I think that only the zeroes function 
> # allows you to declare a piddle with a specific data type


perldl> ?sequence
Module  PDL::Basic
   sequence
     Create array filled with a sequence of values

      $a = sequence($b); $a = sequence [OPTIONAL TYPE], @dims;

     etc. see zeroes.

      perldl> p sequence(10)
      [0 1 2 3 4 5 6 7 8 9]
      perldl> p sequence(3,4)
      [
       [ 0  1  2]
       [ 3  4  5]
       [ 6  7  8]
       [ 9 10 11]
      ]

     Docs from /c/site/perl/lib_pdl/cygwin-thread-multi-64int/PDL/Basic.pm

So you can do:

perldl> $a = sequence(byte, 3, 10, 10);

perldl> p $a->info
PDL: Byte D [3,10,10]

 > my $pdl = zeroes(byte, 3, 10, 10);
> # Set values. Use in place to be sure we don't get another allocation, 
> which may be the wrong type.
> # Note that the sequence wraps back to zero after hitting 256, because 
> they're bytes!
> $pdl->inplace->sequence;
> 
> # Now for a really silly animation - turn all the pixels white
> for (my $i = 0; $i < 300; $i++) {
>   $pdl()->clump(-1)->($i) = 255;
>   # Do something with piddle data here.
> }
> 
> --------%<--------
> 
> Is that a bit clearer?  Does anybody have a better sample?

You could use the PDL life example of threading that Matt posted
earlier today.  Just make an empty $sdl piddle with dims [3,N,M],
a $life piddle with shape [N,M] for the life updates, init $life,
then copy each update from the $life to the $sdl, maybe like:

$sdl .= $life(*3);