CODEWITHSUNDEEP
perlhashiteratorperl-data-structures
Jane Wilkie
Jane Wilkie

Reputation: 1743

Iterating over a complex data structure

I have what appears to be a hash of a hash of an array of hashes. I'm trying to pull some values out and I'm stumped (this is way deeper than I would go with a structure. It looks like this.....

%htest = (
  8569 => {
    4587 => [
           {
            date=> "2011-01-15",
            approved=> 1,
           },
           { 
            date=> "2011-01-12",
            approved=> 1,
           },
           ],
    1254 => [
           {
            date=> "2011-01-12",
            approved=> "",
           },
           { 
            date=> "",
            approved=> 1,
           },
           ],
        },
);

Trying to iterate over this thing is giving me a massive headache. I'm trying to access the number of elements under the second hash value (4587 and 1254). The number of those elements where approved="1" and the number of elements where the date contains a value.

If I could iterate over them I sure I could shove what I need into a less complex structure but so far I'm at a loss.

I got this far...

while (my ($id, $surveyhash) = each %{ $htest{'8569'} } ){
    print "$enumid = $subhash\n";
    print Dumper $subhash."\n";
}

That gives me the "4587" and "1254" but trying to do a dumper on $subhash just gives me....

4587 = ARRAY(0x9a9ffb0)
$VAR1 = 'ARRAY(0x9a9ffb0)
';
1254 = ARRAY(0x9a91788)
$VAR1 = 'ARRAY(0x9a91788)
';

Any idea how to iterate over this monstrosity? Janie

Upvotes: 2

Views: 1145

Answers (3)

zgpmax
zgpmax

Reputation: 2847

Counting match cases can be done with "scalar grep".

my ($approved, $date_has_value) = (0, 0);

for my $v1 (values %htest) {
    for my $v2 (values %$v1) {
        $approved       += scalar grep { $$_{approved} eq '1' } @$v2;
        $date_has_value += scalar grep { $$_{date}     ne ''  } @$v2;
    }
}

Upvotes: 2

ardnew
ardnew

Reputation: 2086

Here's a fairly explicit iteration that should help get you started

my ($num_approved, $num_date) = (0, 0);

# outer hash
while (my ($ka, $va) = each %htest)
{
  # inner hash
  while (my ($kb, $vb) = each %{$va})
  {
    # each hash inside the array
    foreach my $h (@{$vb})
    {
      $num_approved += ${$h}{"approved"} == 1;
      $num_date     += length(${$h}{"date"}) > 0;
    }
  }
}

Upvotes: 2

xpapad
xpapad

Reputation: 4456

Your structure has typos, you need commas between the innermost hashes and a parenthesis at the end (rather than a curly bracket)

Once you fix it you can use something like this:

my $approved = 0, my $date_has_value = 0;
while ( my ($k,$vref) = each %htest ) {
    while ( my ($k,$v) = each %$vref ) { 
        # Now you're inside the inner hash, so there will be 2 iterations
        # with $k 4587 and 1254
        foreach my $item (@$v) {
            # Now each $item is a reference to the innermost hashes
            $approved++ if $item->{approved} == 1;
            $date_has_value++ if $item->{date};
        }
    }
}

Upvotes: 4

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