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# - requires both bad-value support and PGPLOT
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use File::Basename qw(&basename &dirname);
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# check for bad value support
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my $bvalflag = $PDL::Config{WITH_BADVAL} || 0;
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# This forces PL files to create target in same directory as PL file.
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# This is so that make depend always knows where to find PL derivatives.
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($file = basename($0)) =~ s/\.PL$//;
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if ($Config{'osname'} eq 'VMS' or
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$Config{'osname'} eq 'OS2'); # "case-forgiving"
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open OUT,">$file" or die "Can't create $file: $!";
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print "Extracting $file (WITH bad value support)\n";
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print "Extracting $file (NO bad value support)\n";
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print OUT <<'!NO!SUBS!';
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# Created by BAD2_demo.pm.PL
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# ** DO NOT EDIT THIS FILE **
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package PDL::Demos::BAD2_demo;
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use PDL::Graphics::PGPLOT;
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PDL::Demos::Routines->import();
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print OUT <<'!NO!SUBS!';
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Your version of PDL has been compiled without support for bad
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values, hence this demo doesn't do anything.
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print OUT <<'!NO!SUBS!';
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$ENV{PGPLOT_XW_WIDTH}=0.6;
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$ENV{PGPLOT_DEV}=$^O =~ /MSWin32/ ? '/GW' : "/XSERVE";
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# try and find m51.fits
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$d = File::Spec->catdir( "PDL", "Demos" );
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foreach my $path ( @INC ) {
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my $check = File::Spec->catdir( $path, $d );
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if ( -d $check ) { $m51path = $check; last; }
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barf "Unable to find directory ${m51path} within the perl libraries.\n"
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unless defined $m51path;
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This demo is just a bit of eye-candy to show bad values in action,
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and requires PGPLOT support in PDL. It makes use of the image of
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m51 kindly provided by the IRAF group at the National Optical and
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Astronomical Observatories.
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It also serves to demonstrate that you often don't need to change
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your code to handle bad values, as the routines may 'do it' for you.
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# read in the image ($m51path has been set up by this demo to
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# contain the location of the file)
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$m51 = rfits "$m51path/m51.fits";
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$just = { JUSTIFY => 1 };
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# now, let's mask out the central 30 pixels and display it
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$masked = $m51->setbadif( $m51->rvals({CENTRE=>[128,128]}) < 30 );
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# since imag auto-scales the output, the bad values are not displayed
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# compare the statistics of the images
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# (as $PDL::verbose = 1, stats prints out the answers itself)
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print "Original:\n"; $m51->stats;
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print "Masked:\n"; $masked->stats;
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# let's filter it a little bit
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$filtered = med2d $masked, ones($nb,$nb), { Boundary => 'Truncate' };
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# this is a model of the diffuse component of m51
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imag $filtered, $just;
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# unsharp masking, to bring out the small-scale detail
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$unsharp = $masked - $filtered;
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imag $unsharp, $just;
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# add on some contours showing the large scale structure of the galaxy
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imag $unsharp, $just;
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print OUT <<'!NO!SUBS!';
added
removed
Demos/BAD2_demo.pm.PL
