How do I extract all array values from a hash of hashes

Question

Newbie here. Aplogies if I am missing details.

In perl 5

I have a file that kind of looks like this

precedence = 2
new york
new jersey
florida
precedence = 3
kings
essex
dade
precedence = 1
brooklyn
newark
miami

I have no problem looping through the file and creating a $var that holds the value of precedence and an array (@tmp) that holds the lines until the next "section" (precedence = x)

I need to ultimately push all the sections into a final array in the order of the preference

so

print @final;

results in

 brooklyn
 .....
 new york
 .....
 kings
 .....

NOTE: I never know in advance how many sections there will be or how many lines each section will have

I thought perhapes to make a Hash of hashes and put each array in the HoH

push @{ $hash{"section_2"} }, @tmp ;

but I didnt know

a) if there would be a problem reusing the @tmp array each time i load a section in (after blanking it at the beginning of each loop)

b) I couldnt figure out how to get all values in the array in key "section_2" and push them into @final

Of course there may be a better approach.

Answer 1

An HoH makes no sense. You could use an HoA if you expect a wide variance in precedence levels (1, 1000000, 1000000000),

my $precedence = 0;
my %data;
while (<>) {
   chomp;
   if (/precedence\s*=\s*([0-9]+)\z/) {
      $precedence = $1;
      next;
   }

   push @{ $data{$precedence} }, $_;
}

my @final = map @{ $data{$_} }, sort { $a <=> $b } keys %data;

but an AoA would most likely be a better fit.

my $precedence = 0;
my @data;
while (<>) {
   chomp;
   if (/precedence\s*=\s*([0-9]+)\z/) {
      $precedence = $1;
      next;
   }

   push @{ $data[$precedence] }, $_;
}

my @final = map @$_, grep $_, @data;

Answer 2

Not really sure that I fully understand what you are trying to accomplish but if you want to print each precedence value and then the values from its array, you can try this:

my $hoh;

#This is not how you populate your HoH, I hard code it to simplify
@{$hoh->{2}->{'ARRAY'}} = ('new york', 'new jersey', 'florida');
@{$hoh->{3}->{'ARRAY'}} = ('kings', 'essex', 'dade');
@{$hoh->{1}->{'ARRAY'}} = ('brooklyn', 'newark', 'miami');

foreach my $prcdnc(keys(%$hoh))
{
    print "\nprcdnc = ".$prcdnc;

    my @prcdncAry = @{$hoh->{$prcdnc}->{'ARRAY'}};

    my $prcdncAryStr = join(",", @prcdncAry);

    print "\n\t".$prcdncAryStr;
}