On Jul 7, 4:32 am, chas.ow...@gmail.com ("Chas. Owens") wrote:
> On Wed, Jul 7, 2010 at 06:57, Srinivasa Chaitanya
> T<tschaitanya....@gmail.com> wrote:
> > Thanks that solves the my question. Also I want a write function similar to
> > "map" for hash.
> > I can use map itself for that, but I have to refer the hash variable name in
> > code block.
> > How I write without referring the variable?
>
> > my %as;
> > my %bs;
>
> > $as {'one'} = 1;
> > $as {'two'} = 2;
> > $as {'three'} = 3;
> > $as {'four'} = 4;
> > %bs = map {$_ => ($as{$_} + 10)} keys %as;
>
> snip
>
> You could write a function (see below) that looked like this:
>
> my %bs = hash_map sub { shift() => shift() + 10 }, %as;
>
> But if all you want to do is modify the values of a hash, just say
>
> $_ += 10 for values %as;
>
> If you do not want to not modify %as, then say
>
> my %bs = %as;
> $_ += 10 for values %bs;
>
> But be forewarned, that only creates a shallow copy of %as. If %as is
> a nested data structure, you will need to use some form of deep
> copying function like the [Storable][1] module's dclone to get a copy
> that will not interact with %as.
>
> #!/usr/bin/perl
>
> use strict;
> use warnings;
>
> sub hash_map {
> my ($func, %hash) = @_;
>
> my %ret;
> while (my ($k, $v) = each %hash) {
> my %subhash = $func->($k, $v);
> while (my ($k, $v) = each %subhash) {
> $ret{$k} = $v;
> }
> }
> return %ret;
>
> }
Or, since a humble array can be magically transformed
to a hash, you could simplify slightly to:
sub hash_map {
my ($func, %hash) = @_;
my @ret; # destined for hash-ification
while (my ($k, $v) = each %hash) {
push @ret, $func->($k,$v);
}
return @ret;
}
>
> my %as = (a => 1, b => 2, c => 3);
> my %bs = hash_map sub { $_[0] => $_[1] + 10 }, %as;
> use Data::Dumper;
> print Dumper \%as, \%bs;
--
Charles DeRykus
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