CODEWITHSUNDEEP
arraysperlhash
lalala53__
lalala53__

Reputation: 25

perl delete hash items if not found in an array

I have the following hash: %{$data{$id}{$date}} that includes a large number of dates

and an array @dates that includes a subsection of dates found in the %hash.

What is the best way to loop through my %hash and delete all dates that are not found in @dates array? Once this is done I'd like the %hash to only have the values from @array dates.

I've tried 'delete unless exists' looking at keys after I created a hash from my @dates array but would get missing arguments error.

Upvotes: 2

Views: 223

Answers (2)

blhsing
blhsing

Reputation: 107115

You should loop through the keys of %{$data{$id}} instead.

my %dates = map {$_ => 1} @dates;
exists $dates{$_} or delete $data{$id}{$_} for keys %{$data{$id}};

Upvotes: 4

Borodin
Borodin

Reputation: 126762

As long as the dates in @dates are guaranteed to appear in the hash you can use map

%{ $data{$id} } = map { $_ => $data{$id}{$_} } @dates

Upvotes: 3

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