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Question

，我有以下格式的hashref的二次哈希表：

{ 
    introduction_to_systems => { 
           writer => "John", 
           owner => "Jim" 
    }, 
    management_recipies => { 
           writer => "Jane", 
           owner => "Jim" 
    }, 
etc 
} 

我的问题是，这个哈希是不是很方便。我还希望能够轻松找到由“吉姆”或“约翰”拥有的作家。

基本上我需要这个哈希表的2逆。
在perl中执行此操作的最有效方法是什么？

Answer 1

因为每个所有者和作者都可以拥有并书写很多东西，所以您必须将一系列书籍作为价值来散列。你可以用很多方式做到这一点。例如：

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

my $books = { 
    introduction_to_systems => { 
     writer => "John", 
     owner => "Jim" 
    }, 
    management_recipies => { 
     writer => "Jane", 
     owner => "Jim" 
    }, 
}; 

my (%owns, %wrote); 
for my $book (keys %$books) { 
    my $rec = $books->{$book}; 
    push @{ $owns{ $rec->{owner} } }, $book; 
    push @{ $wrote{ $rec->{writer} } }, $book; 
} 

print "Jim owns @{$owns{Jim}}\n"; 
print "John wrote @{$wrote{John}}\n";