Hilbert curve: Difference between revisions
Added Perl example
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SqrtNegInf (talk | contribs) (Added Perl example) |
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.__. .__. .__. .__. .__. .__. .__. .__. .__. .__. .__. .__. .__. .__. .__. .__. </pre>
=={{header|Perl}}==
<lang perl>use SVG;
use List::Util qw(max min);
use constant pi => 2 * atan2(1, 0);
# Compute the curve with a Lindemayer-system
%rules = (
A => '-BF+AFA+FB-',
B => '+AF-BFB-FA+'
);
$hilbert = 'A';
$hilbert =~ s/([AB])/$rules{$1}/eg for 1..6;
# Draw the curve in SVG
($x, $y) = (0, 0);
$theta = pi/2;
$r = 5;
for (split //, $hilbert) {
if (/F/) {
push @X, sprintf "%.0f", $x;
push @Y, sprintf "%.0f", $y;
$x += $r * cos($theta);
$y += $r * sin($theta);
}
elsif (/\+/) { $theta += pi/2; }
elsif (/\-/) { $theta -= pi/2; }
}
$max = max(@X,@Y);
$xt = -min(@X)+10;
$yt = -min(@Y)+10;
$svg = SVG->new(width=>$max+20, height=>$max+20);
$points = $svg->get_path(x=>\@X, y=>\@Y, -type=>'polyline');
$svg->rect(width=>"100%", height=>"100%", style=>{'fill'=>'black'});
$svg->polyline(%$points, style=>{'stroke'=>'orange', 'stroke-width'=>1}, transform=>"translate($xt,$yt)");
open $fh, '>', 'hilbert_curve.svg';
print $fh $svg->xmlify(-namespace=>'svg');
close $fh;</lang>
[https://github.com/SqrtNegInf/Rosettacode-Perl5-Smoke/blob/master/ref/hilbert_curve.svg Hilbert curve] (offsite image)
=={{header|Perl 6}}==
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