CODEWITHSUNDEEP
perlhashdereference
Charles
Charles

Reputation: 11479

Dereferencing Perl hashrefs

Using Text::Ngram I have

my $c = ngram_counts($text, 3);
my %ct = %($c);

which doesn't work (Scalar found where operator expected). I think this is a combination of not knowing what I'm doing (still not very good with Perl) and being confused about what exactly I'm getting as output from Text::Ngram. Help? I just want to look at the generated n-grams:

my @keys = sort {$ct{$a} cmp $ct{$b} } keys %ct;
foreach my $k (@keys) {
    print "$k: $ct{$k}\n"
}

Edit: Stupid error on my part, thanks everyone.

Upvotes: 7

Views: 17838

Answers (4)

ysth
ysth

Reputation: 98378

There's no need to make a copy into another hash, just use the reference.

my $c = ngram_counts($text, 3);

my @keys = sort {$c->{$a} <=> $c->{$b} } keys %$c;
foreach my $k (@keys) {
    print "$k: $c->{$k}\n"
}

See http://perlmonks.org/?node=References+quick+reference for some easy to remember rules for dealing with references.

Upvotes: 3

sergio
sergio

Reputation: 69027

Would you try this?

my $c = ngram_counts({}, $text, 3);

Upvotes: 0

Zaid
Zaid

Reputation: 37136

Use curly braces to dereference the hash reference:

my %ct = %{ $ct };  # %$ct would also work

And you probably want to use <=> for numerical sorting instead of the ASCII-betical sorting cmp.

Upvotes: 16

gpojd
gpojd

Reputation: 23055

Use curly braces: 

my %ct = %{ $c };

Upvotes: 7

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