Question

I have the following hashref of hashrefs structure:

$hashref = {
    user1 => {
        key1 => "unique_value1",
        ...
        key99 => "value1_99"
    },
    ...
    user26 => {
        key1 => "unique_value2",
        ...
        key99 => "value1_99"
    },

    user99 => {
        key1 => "unique_value1",
        ...
        key99 => "value99_99"
    },
};

What I want out:

$hashref = {
    "unique_value1" => ["user1","user99"],
    "unique_value2" => ["user26"]
};

I’ve historically built the inverted map on create, but I’m getting lazy.

Any one line sugar I could use for this?

Thank you.

Answer 1

One way:

my $h; 
push (@{$h->{$hashref->{$_}{key1}}}, $_) for keys %$hashref;