Contributed by Anonymous Monk
on Mar 30, 2001 at 00:46 UTC
Q&A
> sorting
Description: How do I do a natural sort on an array?
i.e. each array element is contains a string made up of numbers and letters. Answer: How do I do a natural sort on an array? contributed by tye my @sorted= grep {s/(^|\D)0+(\d)/$1$2/g,1} sort
grep {s/(\d+)/sprintf"%06.6d",$1/ge,1} @data;
See RE: RE: Re: Sorting on Section Numbers some important style comments.
Features and limitations:
- Strips extra leading zeros from digit strings
- Doesn't handle floating point numbers at all well
- Sorts negative integers in reverse after positive integers
- Uses very little extra memory
- You must specify the maximum number of digits your
integers will have (6 in the above code)
| Answer: How do I do a natural sort on an array? contributed by tye my %data;
foreach my $data ( @data ) {
( my $sort= $data ) =~ s/(0*)(\d+)/
pack("C",length($2)) . $1 . $2 /ge;
$data{$sort}= $data;
}
my @sorted= @data{ sort keys %data };
Bugs and features
- Doesn't properly sort decimal values like 12.34
- Sorts negative integers in reverse after positive integers
- Requires more memory than other methods I'll be adding
| Answer: How do I do a natural sort on an array? contributed by indigo @a = sort @b;
will sort lexigraphically.
@a = sort { $a <=> $b } @b;
will sort numerically.
@a = sort &naturally @b;
will sort "naturally", where naturally() is a compare routine of your own devising.
perldoc -f sort for more info. | Answer: How do I do a natural sort on an array? contributed by Dominus I'm not exactly sure what you want (it would have helped if you had provided an
example) but here's what I use:
sub byfile {
my @a = split /(\d+)/, $a;
my @b = split /(\d+)/, $b;
my $M = @a > @b ? @a : @b;
my $res = 0;
for (my $i = 0; $i < $M; $i++) {
return -1 if ! defined $a[$i];
return 1 if ! defined $b[$i];
if ($a[$i] =~ /\d/) {
$res = $a[$i] <=> $b[$i];
} else {
$res = $a[$i] cmp $b[$i];
}
last if $res;
}
$res;
}
This may be more complicated than you need. Given the following:
53 7 119 53red
red5 red6 red7 red67 red6.jpg red12.jpg
green4.jpg
blue2.jpg blue1000.jpg blue2.jpg58
it produces the following output:
7
53
53red
119
blue2.jpg
blue2.jpg58
blue1000.jpg
green4.jpg
red5
red6
red6.jpg
red7
red12.jpg
red67
Lucs St. Louis also suggests:
while (defined (my $A = shift @a) and defined (my $B = shift @b)) {
$res = ($A =~ /\d/) ? $A <=> $B : $A cmp $B;
return $res if $res;
}
return defined $A ? -1 : 1;
Hope this helps.
| Answer: How do I do a natural sort on an array? contributed by salva Sort::Key::Natural is fast, can handle numbers of unlimited size and doesn't have problems with unicode:
use Sort::Key::Natural qw(natsort);
my @sorted = natsort @data;
| Answer: How do I do a natural sort on an array? contributed by ihb You can use Sort::Naturally. | Answer: How do I do a natural sort on an array? contributed by Jammerwoch I wrote the following before finding the delightful Sort::Naturally library function. I reccommend using that over what I've done, but maybe people are curious how it might be done. Or maybe someone needs to fine-tune or customize it.
The following code is NOT efficient. In particular, the calling of naturalSortInner with $a and $b as arguments completely eliminates the efficiency of having $a and $b. However, it was necessary for the recursive nature of naturalSortInner.
#!/usr/bin/perl
sub naturalSortInner {
$x = uc( shift );
$y = uc( shift );
if( !($x =~ /\d+(\.\d+)?/) ) {
return $x cmp $y;
}
$xBefore = $`;
$xMatch = $&;
$xAfter = $';
if( !($y =~ /\d+(\.\d+)?/) ) {
return $x cmp $y;
}
if( $xBefore eq $` ) {
if( $xMatch == $& ) {
return naturalSortInner( $xAfter, $' );
} else {
return $xMatch <=> $&;
}
} else {
return $x cmp $y;
}
print "\n<before: '$xBefore', match: '$xMatch', after: '$xAfter'>\
+n";
}
sub naturalSort {
naturalSortInner( $a, $b );
}
@arr = (
'beta',
'Alpha',
'Gamma1',
'Gamma',
'23',
'5',
'Version1',
'Version1.1',
'Version1.2',
'Version11.1-Sub1',
'Version11.1-Sub10',
'Version11.1-Sub3',
'x23sub5',
'Version2',
'Version2.1',
'GammaGlobulin',
'Gamma10',
'c',
'Gamma2',
'Gamma3',
);
print join( "\n", sort naturalSort @arr ) . "\n";
|
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