OK then.
PGPLOT apparently gets confused if all the values in one dimension
are exactly the same, because it cannot find a minimum and a maximum
to fit the axis to. This normally is plotted correctly (or exits with an error
if I remember correctly)
but in your case it does not and it plots the points incorrectly.
I think this looks like a bug in PGPLOT (or the functions that call it).
To circumvent it you can call the env environment before plotting:
perldl> $w->env(min($x),max($x),0,2)
perldl> $w->points($x,$y)
Hope this helps ;=)
Xavier
On Jan 31, 2008 4:11 PM, Sebastian Perez <[EMAIL PROTECTED]> wrote:
> Hi,
>
> BITPIX = -32 is a valid value and just means that the array is
> represented as IEEE 32-bit floating point values, so that shouldn't
> be a problem.
>
> Cheers,
> Seb
>
>
>
> On 31 Jan 2008, at 14:59, Xavier Calbet wrote:
>
> > One more thing, you might want to have a look at your fits header
> > before
> > you write your FITS file (print $hdr->{BITPIX} maybe) just to
> > check and
> > see whether you have garbage in there or not. In any case you can also
> > do
> >
> > $hdr->{BITPIX}=32
> >
> > before you write the file.
> >
> > Xavier Calbet
> >
> >
> > On Jan 31, 2008 3:55 PM, Xavier Calbet <[EMAIL PROTECTED]> wrote:
> >> When I read your original file I get (as you do) different results
> >> with the plotting
> >> and printing. If I modify BITPIX=-32 to BITPIX=32 I get consistent
> >> results.
> >>
> >> Cheers,
> >>
> >> Xavier Calbet
> >>
> >>
> >> On Jan 31, 2008 3:41 PM, PAUL <[EMAIL PROTECTED]> wrote:
> >>> Hmmm... that does seem strange, but then looking at all the headers
> >>> of the FITS files I have, they all have BITPIX=-32. (Even FITS which
> >>> have not been hacked using PDL). Is BITPIX actually still used?
> >>>
> >>> The sub which I used to write many FITS is here:
> >>>
> >>>
> >>> ##################################################
> >>> sub WriteFits { ##################################
> >>> for($i=0;$i<$N_data;++$i) {
> >>> ($suffix) = @_;
> >>> $fitsname = $allnames[$i].$suffix.".fits";
> >>> $newpid = $new_master_data(:,:,$i);
> >>> $newpid = $newpid->float;
> >>> $minpid = min($newpid);
> >>> $maxpid = max($newpid);
> >>> $hdr->{MINVAL} = $minpid;
> >>> $hdr->{MAXVAL} = $maxpid;
> >>> $newpid -> sethdr($hdr);
> >>> wfits $newpid, $fitsname;
> >>> print "FITS file FITS/$fitsname created!\n";
> >>> system 'mv',$fitsname,$fitsdirectory;
> >>> }
> >>> system 'mv',$filename,$donedirectory;
> >>> } # Ends the WriteFits sub. ######################
> >>> ##################################################
> >>>
> >>> However, I've used this same routine to make hundreds of other FITS
> >>> in this way, and I've never seen this weird problem before!
> >>>
> >>> cheers,
> >>>
> >>> Paul
> >>>
> >>>
> >>>
> >>>
> >>> On 31 Jan 2008, at 14:17, Xavier Calbet wrote:
> >>>
> >>>> Don't know if it has anything to do with it, but your fits
> >>>> header has a value of BITPIX=-32 (negative!!!)
> >>>> This value is the number of bits per pixel in the image
> >>>> and should always be positive.
> >>>> If foo.fits has been written by PDL then it is strange.
> >>>> Can you extract the PDL code where you write this file?
> >>>>
> >>>> Xavier Calbet
> >>>>
> >>>>
> >>>> On Jan 31, 2008 2:58 PM, PAUL <[EMAIL PROTECTED]> wrote:
> >>>>> Hi,
> >>>>>
> >>>>> I've encountered a strange effect when reading a fits file in the
> >>>>> usual way (written with wfits, read with rfits as I usually do).
> >>>>>
> >>>>> The problem is, when I try and plot the piddle as a scatter plot
> >>>>> ($win->points($x,$y)) it plots completely different values than
> >>>>> when
> >>>>> you simply print the piddle to the screen.
> >>>>> I've tried writing the data to an ASCII file using "wcols" and
> >>>>> then
> >>>>> re-reading it, but this strange problem remains.
> >>>>>
> >>>>> What's going wrong? I've attached the fits file to the email.
> >>>>>
> >>>>> thanks,
> >>>>>
> >>>>> Paul
> >>>>>
> >>>>>
> >>>>> _______________________________________________
> >>>>> Perldl mailing list
> >>>>> [email protected]
> >>>>> http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
> >>>>>
> >>>>>
> >>>
> >>>
> >>
> >
> > _______________________________________________
> > Perldl mailing list
> > [email protected]
> > http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
>
>
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