Hi Matthew,

Thanks for all the help! That was indeed what I was trying to
understand. I must admit I looked at the PGplot documentation, but got
confused and didn't understand what transform was about. So now I
know, thanks!

Cheers,
Michiel


On Thu, Nov 12, 2009 at 5:17 PM, Matthew Kenworthy
<[email protected]> wrote:
>> #----------------------------------
>> #!/usr/bin/perl
>> use PDL;
>> use PDL::Graphics::PGPLOT;
>>
>> imag (sin(rvals(200,200)+1));
>>
>> #----------------------------------
>>
>> How do I now change the x axis so the 0 becomes -100,100 becomes 0 and
>> 200 becomes 100 ?
>
> TO set the limits of the viewport, you can use:
>
> env(-100,100,-100,100);
> imag (sin(rvals(200,200)+1));
>
> ...but what I suspect you *really* want to do is make it so that the
> PDL coordinates are remapped from (0:199,0:199) into PGPLOT
> coordinates, and for that you need the TRANSFORM keyword in imag:
>
>
> # always put your image in a separate piddle, since sometimes the option hash
> # doesn't make it through to imag
> # not sure why! I suspect it has something to do with the parentheses
> in your original expression
>
> # set up plot window
> env(-100,100,-100,100);
>
> # set up image to put in imag
> $im = (sin(rvals(200,200)+1));
>
> $xoffset = -100;
> $yoffset = -100;
>
> imag $im,{ TRANSFORM=>pdl([$xoffset,1,0,$yoffset,0,1]) };
>
> The explanation of the numbers in TRANSFORM is explained in about line
> 72 of the
> PDL::Graphics::PGPLOT::Window documentation.
>
> For all the information you need:
>
> pdldoc PDL::Graphics::PGPLOT::Window
>  (yeah, it's a long string for the help page, but it's essential
> reading for PGPLOT in PDL!)
>
> Cheers,
>
> Matt
>
> --
> Matthew Kenworthy / Assistant Astronomer / Steward Observatory
> 933 N. Cherry Ave. / Tucson AZ 85721 / vox 520 626 6720
>

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