如何排序perl哈希?

Question

我有下面的哈希结构，哈希的哈希。

$VAR1 = { '191' => { 'test1' => { 'score' => '9.18' }, 'test2' => { 'score' => '2.84' }, 
'test3' => { 'score' => '15.62' }, 'test4' => { 'score' => '11.84' }, 
'190' => { 'test1'=> { 'score' => '13.28' }, 'test2' => { 'score' => '-47.56' }, 
'test3' => { 'score' => '18.50' }, 'test4' => { 'score' => '14.88' } } }

我正试图根据'score'值对哈希进行排序。排序应该只发生在主键'191'和'190'的内部。

$VAR1 = { '191' => {'test3' => { 'score' => '15.62' }, 'test4' => { 'score' => '11.84' }
'test1' => { 'score' => '9.18' }, 'test2' => { 'score' => '2.84' }, 

​ '190' => { 'test3' => { 'score' => '18.50' }, 'test4' => { 'score' => '14.88' }
'test1'=> {'score' => '13.28' }, 'test2' => { 'score' => '-47.56' } } }

排序将根据降序评分值进行。

我试过下面的代码，但它有点基于主键。我需要的输出如预期的哈希结构所示。

my @sort_by_rank;
for my $key1 (keys %rankBased) {
for my $key2 (keys %{$rankBased{$key1}}) {
@sort_by_rank = sort{ $rankBased{$b}{$key2}{score} <=> $rankBased{$a}{$key2}{score}
} keys %rankBased;
}   
}

这里%rankBased是哈希值。

请帮助。

Answer 1

不能对散列进行排序，但可以对散列的键列表进行排序。

for my $student_id (keys %tests_by_student_id) {
my $tests = $tests_by_student_id{$student_id};
my @sorted_test_ids =
sort { $tests->{$b}{score} <=> $tests->{$a}{score} }
keys(%$tests);
# Do something with the student's sorted tests here.
}

(无意义的%rankBased重命名为%tests_by_student_id)

---

以上是伟大的是你想做的事情与每个学生。但是如果你真的想"排序"散列，你需要切换到一个不同的结构。

for my $student_id (keys %tests_by_student_id) {
# This next line is the same as 
# my $tests = $tests_by_student_id{$student_id};
# except changing $tests also changes
# $tests_by_student_id{$student_id}.
for my $tests ($tests_by_student_id{$student_id}) {
$tests = [
sort { $b->{score} <=> $a->{score} }
map { { id => $_, %{ $tests->{$_} } } }
keys(%$tests)
];
}
}

这生产

$VAR1 = {
'191' => [ { id => 'test3', score =>  15.62 },
{ id => 'test4', score =>  11.84 },
{ id => 'test1', score =>   9.18 },
{ id => 'test2', score =>   2.84 } ],
'190' => [ { id => 'test3', score =>  18.50 },
{ id => 'test4', score =>  14.88 },
{ id => 'test1', score =>  13.28 },
{ id => 'test2', score => -47.56 } ],
};