在Perl中,我如何按值的频率排序？

Question

我正在尝试创建一个程序来计算数据文件列中出现的不同值.所以,如果列的可能值是A,B,C,那就像是这样的.输出类似于

A   456
B   234
C   344

通过做这样的事情,我已经能够轻松获得A,B和C的运行计数

my %count; 
for my $f (@ffile) {

    open F, $f || die "Cannot open $f: $!";

    while (<F>) {
       chomp;
       my @U = split / /;

       $count{$U[2]}++; 
    }

}
   foreach my $w (sort keys %count) {
         printf $w\t$count{$w};
     }

例如,我在计算给定路径中的文件的第二列.

如何通过计数而不是键(或值A,B,C)对printf的输出进行排序 -

A   456
C   344
B   234

Answer 1

这是一个FAQ:

perldoc -q sort

use warnings;
use strict;

my %count = (
    A => 456,
    B => 234,
    C => 344
);

for my $w (sort { $count{$b} <=> $count{$a} } keys %count) {
    print "$w\t$count{$w}\n";
}

__END__
A       456
C       344
B       234

Answer 2

for my $w (sort {$count{$b} <=> $count{$a}} keys %count) {
    print "$w\t$count{$w}\n";
}