Re: Hash assignments using map

[japhy]

in reply to Hash assignments using map

In addition to what others have said, you could do:

my @to_keep = (...);
my %keepers;
@keepers{@to_keep} = ();

which you would then test with exists $keepers{$x}. Althought I'm curious why you need the %keepers hash if you have the @to_keep array.

[njcodewarrior]

Hi japhy

Not to beat a dead horse here, but to answer your question:

I'm checking the keys in another hash against those in %keepers. If a keys exists in this other hash, but NOT in %keepers, I want to eliminate it from the hash. See this node for further explanation.

Anyways, thanks for the clarification

njcodewarrior

[japhy]

Right. My point is, why not loop over the elements in @keepers, rather than the keys of the other hash?

my %big_hash = (...);
my @to_keep = ('abc', 'xyz');

%big_hash = map { exists($big_hash{$_}) ? ($_ => $big_hash{$_}) : () }
+ @to_keep;
# or
%big_hash = map { $_ => $big_hash{$_} } grep { exists $big_hash{$_} } 
+@to_keep;