Re: How I learned to stop worrying and love the hash slice. (boo)

[PrakashK]

I frequently use hash slices to eliminate duplicates from an array.

A simplified example:

my @a = (1,2,3,2,1);
my %a;
@a{@a} = (1) x @a;
my @unique_a = keys %a;

Of course, this does not preserve the order of the elements as they were in original array @a.

[blakem]

Perhaps grep might work better here?

my @a = (1,2,3,2,1);
my %seen;
my @unique_a = grep {!$seen{$_}++} @a;

print "A:      $_\n" for (@a);
print "Unique: $_\n" for (@unique_a);

Assuming you wanted to keep the first occurance, this will preserve the original order.

Or you can use map to create your %a hash.

my @a = (1,2,3,2,1);
my %a = map {$_=>1} @a;
my @unique_a = keys %a;

print "A:      $_\n" for (@a);
print "Unique: $_\n" for (@unique_a);

-Blake