Perl - Transforming an anonymous array

Question

I can manipulate a single array element and add a reference to the array as a value in a hash. Easy. For example, this achieves the desired result:

# split the line into an array
my @array = split;

# convert the second element from hex to dec
$array[1] = hex($array[1]);

# now add the array to a hash
$hash{$name}{ ++$count{$name} } = \@array;

My question: Is it possible to do the same thing using an anonymous array? I can get close by doing the following:

$hash{$name}{ ++$count{$name} } = [ split ];

However, this doesn't manipulate the second index (convert hex to dec) of the anonymous array. If it can be done, how?

Borodin · Accepted Answer · 2013-04-05 04:09:46Z

4

What you are asking for is this

my $array = [ split ];

$array->[1] = hex($array->[1]);

$hash{$name}{ ++$count{$name} } = $array;

But that may not be what you mean.

Also, rather than using sequential numbered hash keys you would probably be better off using a hash of arrays, like this

my $array = [ split ];

$array->[1] = hex($array->[1]);

push @{ $hash{$name} }, $array;

You need a way to access the array to say what you want to modify, but you could modify it after pushing it onto the hash, like this:

push @{ $hash{$name} }, [split];
$hash{$name}[-1][1] = hex($hash{$name}[-1][1]);

although that's really not very nice. Or you could

push @{ $hash{$name} }, do {
    my @array = [split];
    $array[1] = hex($array[1]);
    \@array;
};

or even

for ([split]) {
    $_->[1] = hex($_->[1]);
    push @{ $hash{$name} }, $_;
}

edited Apr 5, 2013 at 4:09

answered Apr 5, 2013 at 0:55

Borodin

127k9 gold badges72 silver badges146 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Steve Over a year ago

Thank-you Borodin. I guess my question was - can $array also be anonymous? I can see now that it can't be. I will also implement you're HoA suggestion. Cheers.

ysth Over a year ago

$array is a reference to an anonymous array; does that help? You could do $hash{$name}{ ++$count{$name} } = map [$_->[0], hex($_->[1]), @$_[2..$#$_]], [split]; but that would be silly

imran Over a year ago

here is another variation on this theme: $hash{$name}{ ++$count{$name} } = (map { $_->[1] = hex($_->[1]); $_ } ([split]))[0];

ysth Over a year ago

oh, oops, you are right, the ()[0] is needed around the map (or parens around $hash{$name}{++$count{$name}} to make it a list assignment)

Borodin Over a year ago

All imran and ysth's options do is store the array reference in $_ instead of an explicit $array.

Collectives™ on Stack Overflow

Perl - Transforming an anonymous array

1 Answer 1

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related