NAME
Hash::Subset - Produce subset of a hash
VERSION
This document describes version 0.003 of Hash::Subset (from Perl distribution Hash-Subset), released on 2019-07-10.
SYNOPSIS
use Hash::Subset qw(hash_subset hashref_subset);
# using keys specified in an array
my %subset = hash_subset ({a=>1, b=>2, c=>3}, ['b','c','d']); # => (b=>2, c=>3)
my $subset = hashref_subset({a=>1, b=>2, c=>3}, ['b','c','d']); # => {b=>2, c=>3}
# using keys specified in another hash
my %subset = hash_subset ({a=>1, b=>2, c=>3}, {b=>20, c=>30, d=>40}); # => (b=>2, c=>3)
my $subset = hashref_subset({a=>1, b=>2, c=>3}, {b=>20, c=>30, d=>40}); # => {b=>2, c=>3}DESCRIPTION
FUNCTIONS
None exported by default.
hash_subset
Usage:
my %subset = hash_subset (\%hash, \@keys);
my $subset = hashref_subset(\%hash, \@keys);
my %subset = hash_subset (\%hash, \%another_hash);
my $subset = hashref_subset(\%hash, \%another_hash);Produce subset of %hash, returning the subset hash (or hashref, in the case of hashref_subset function).
Perl lets you produce a hash subset using the hash slice notation:
my %subset = %hash{"b","c","d"};The difference with hash_subset is: 1) hash slice is only available since perl 5.20 (in previous versions, only array slice is available); 2) when the key does not exist in the array, perl will create it for you with undef as the value:
my %hash = (a=>1, b=>2, c=>3);
my %subset = %hash{"b","c","d"}; # => (b=>2, c=>3, d=>undef)So basically hash_subset is equivalent to:
my %subset = %hash{grep {exists $hash{$_}} "b","c","d"}; # => (b=>2, c=>3)and available for perl earlier than 5.20.
hashref_subset
See "hash_subset".
HOMEPAGE
Please visit the project's homepage at https://metacpan.org/release/Hash-Subset.
SOURCE
Source repository is at https://github.com/perlancar/perl-Hash-Subset.
BUGS
Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=Hash-Subset
When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.
SEE ALSO
Some other hash utilities: Hash::MostUtils
AUTHOR
perlancar <perlancar@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2019 by perlancar@cpan.org.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.