Burrows–Wheeler transform: Difference between revisions
Added Perl example
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SqrtNegInf (talk | contribs) (Added Perl example) |
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</pre>
=={{header|Perl}}==
{{trans|Perl 6}}
<lang perl>use utf8;
binmode STDOUT, ":utf8";
use constant STX => '👍 ';
sub transform {
my($s) = @_;
my($t);
warn "String can't contain STX character." and exit if $s =~ /STX/;
$s = STX . $s;
$t .= substr($_,-1,1) for sort map { rotate($s,$_) } 1..length($s);
return $t;
}
sub rotate { my($s,$n) = @_; join '', (split '', $s)[$n..length($s)-1, 0..$n-1] }
sub ɯɹoɟsuɐɹʇ {
my($s) = @_;
my @s = split '', $s;
my @t = sort @s;
map { @t = sort map { $s[$_] . $t[$_] } 0..length($s)-1 } 1..length($s)-1;
for (@t) {
next unless /${\(STX)}$/; # interpolate the constant
chop $_ and return $_
}
}
for $phrase (qw<BANANA dogwood SIX.MIXED.PIXIES.SIFT.SIXTY.PIXIE.DUST.BOXES>,
'TO BE OR NOT TO BE OR WANT TO BE OR NOT?') {
push @res, 'Original: '. $phrase;
push @res, 'Transformed: '. transform $phrase;
push @res, 'Inverse transformed: '. ɯɹoɟsuɐɹʇ transform $phrase;
push @res, '';
}
print join "\n", @res;</lang>
{{out}}
<pre>Original: BANANA
Transformed: BNN👍 AAA
Inverse transformed: BANANA
Original: dogwood
Transformed: 👍 ooodwgd
Inverse transformed: dogwood
Original: SIX.MIXED.PIXIES.SIFT.SIXTY.PIXIE.DUST.BOXES
Transformed: TEXYDST.E.IXIXIXXSSMPPS.B..E.👍 .UESFXDIIOIIITS
Inverse transformed: SIX.MIXED.PIXIES.SIFT.SIXTY.PIXIE.DUST.BOXES
Original: TO BE OR NOT TO BE OR WANT TO BE OR NOT?
Transformed: OOORREEETTRTW BBB ATTT NNOOONOO👍 ?
Inverse transformed: TO BE OR NOT TO BE OR WANT TO BE OR NOT?</pre>
=={{header|Perl 6}}==
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