Grepping on array

[hotshot]

Hi all!

I have two arrays, I need to get all the values values in one array that DON'T appear in the second array, example:

my @arr1 = qw(a b c d e f g h);
my @arr2 = qw(d a e);

# needed array
@result = qw(b c f g h);

Anyone?

[diotalevi]

I would feel silly quoting the documentation. Execute perldoc -q "difference of two arrays" to see the standard answer. This is in perlfaq4, btw.

[Abigail-II]

perldoc -q duplicate

Abigail

[ctilmes]

You can also use List::Compare to do this sort of thing:

my @arr1 = qw(a b c d e f g h);
my @arr2 = qw(d a e);

my @result = List::Compare->new(\@arr1, \@arr2)->get_Lonly;

# @result = qw(b c f g h);

[herveus]

Howdy!

my %first = map { $_ => 1 } @arr2;
@result = grep !exists $first{$_}, @arr1;

%first is a hash whose keys are the distinct values in @arr2. The grep returns a list of the values in @arr1 that don't exist in %first, thus eliminating values in @arr2.

[dragonchild]

This is a very basic set arithmetic question. (You're looking for the result set when subtracting @arr2 from @arr1.)

[monkey_boy]

Set::scalar
esp. usefull if your manipulations get more complex.