Question

使用Perl，我想只打印每个列表中的重复（重复）值。值应至少出现2次（2次或更多次）。每个列表（行）应单独考虑。

例如，给定输入：

abc 51082 6457 31072 5575 5488 4842 16567 151

cde 5575 3674 8150  5575 3674 8150

fgh 5737 6887 48278 3674 34399 3674 8150

我想要以下输出：

abc 
cde 5575 3674 8150
fgh 3674

我编写了以下源代码，但它没有提供正确的输出：

#!/usr/bin/perl -w

open FH, "input.txt";
@a=<FH>;

my %count_of;

foreach $tmp (@a) 
{
    foreach $word (split /\s/, $tmp) 
    {
        $count_of{$word}++;

        if ($count_of{$word} >=2)
        {
            print "$word\n";
        }
    }
}

exit;

有人可以指导我对代码需要进行哪些更改？谢谢！

Answer 1

这是一个工作版本。查看代码中的注释以了解更正

#!/usr/bin/perl

# always use strict and warnings: this will help you to find errors
use warnings;
use strict;

open FH, 'input.txt';

# always declare variables
my @a=<FH>;

# you should close file handles
close FH;

# declare $tmp
foreach my $tmp (@a) {

    # you need to process the first element differently since you
    # want to always print it
    my @row = split /\s/, $tmp;

    # you should check for empty rows
    if (@row == 0) {
        # empty row
        next;
    }

    # removes the first element
    my $header = shift @row;

    # the first element is always printed
    print $header;

    # this should be local otherwise you are counting globally
    # a new declaration will give you a new hash
    my %count_of;

    # declare $word
    foreach my $word ( @row ) {

        # you should not increment an undefined variable
        if ( $count_of{$word} ) {
            $count_of{$word} = 1;
        } else {
            $count_of{$word}++;
        }

        # just print the second time you see the word
        if ( $count_of{$word} == 2) {
            print " $word";
        }

    }

    print "\n";

}

# it is good practice to return true at the end of a script (no need to exit)
1;

这会产生：

abc
cde 5575 3674 8150
fgh 3674

Answer 2

grep结合哈希来跟踪看到的值，非常适合这类问题：

#!/usr/bin/env perl
use strict;
use warnings;

my $file = "input.txt";
open my $fh, "<", "$file" or die "Unable to open $file: $!\n";

while (<$fh>) {
    chomp;
    my ($key, @values) = split or next; # skip empty rows
    my (%seen, @dupl);
    @dupl = grep $seen{$_}++ == 1, @values;
    print "$key @dupl\n";
}

输出：

abc 
cde 5575 3674 8150
fgh 3674

请注意，or（与||相对）在两种情况下都至关重要。此外，您应始终检查您尝试打开文件的结果use strict;，并最好将-w替换为use warnings;以便移植。无论如何，当你要逐行处理它时，也没有必要啜饮你的文件。

Answer 3

#!/usr/bin/perl -w

use strict;

while (<>) {
    chomp;
    my ($name, @inp) = split /\s+/ or next;
    my %counts;
    for (@inp) { $counts{$_}++ }
    print join (' ', $name, map { $counts{$_} > 1 ? $_ : () } keys %counts), "\n";
}

Perl：仅打印列表中的重复值

3 个答案: