Re: What I Most Recently Learned in Perl, But Should Have Already Known

Map and grep. Especially for set functions, e.g. (untested code, but that should give the idea)

my @a=(1,2,3,4,5);
my @b=(4,5,6,7,8);

my %a = map { $_ => 1 } @a;
my %b = map { $_ => 1 } @b;

my @intersection = grep { exists $a{$_} } @b;
my @intersection_complement = grep { !exists $a{$_} } @b;
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Re^2: What I Most Recently Learned in Perl, But Should Have Already Known by pKai (Priest) on Aug 23, 2006 at 08:49 UTC
That reminds me that some time back I tried to get a grip on hash slices. In similar use to your example: `my @intersection = grep {defined} @{{map {$_=>$_} @a}}{@b}` Though in everyday life I prefer your method, since I tend to get headache from thinking about that slices and also definitely got the syntax and/or semantics wrong the first time always.	[reply] [d/l]