mapping two arrays into anon hash

agoth has asked for the wisdom of the Perl Monks concerning the following question:

Hola, I am trying to map two fixed and known lenght lists into a hash, preferably without using variables.

I want to replace myfunc below with a short but legible bit of code, the last attempt below ends up using $_, @_ and %_ which is a bit mean.

Any better offers??

my @usual = qw ( data email stuff );   #--- fixed length

my $i = 0;
my %hash;

my @input = (
    #--- rather have no function
    { username => 'fred1', myfunc ( 12, 56, 78 ) },            
    #--- no use if have to reset $i
    { username => 'fnerk', map { $usual[ $i++ ] => $_ } (33, 44, 55) }
+,
    #--- hmm
    { username => 'aargh', map { @hash{@usual} = @$_; %hash } [ 33, 44
+, 55 ] },
    #--- longwinded
    { username => 'fnerk', map { $tmp = shift @usual; 
 push @usual,$tmp; $tmp, $_ } (33, 44, 55) },
    #--- heinous
    { username => 'aargh', map { @_{ @usual } = @$_; %_ } [ 33, 44, 55
+ ] },

);

sub myfunc {
    my %flib;
    @flib{ @usual } = @_;
    return %flib;
}

for ( @input ) {
    my %local = %$_;
    for (sort keys %local ) {
       print "key : $_ : val : $local{$_} : ";
    }
    print "\n";
}
[download]

Comment on mapping two arrays into anon hash Download Code

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Re: mapping two arrays into anon hash by Masem (Monsignor) on Jan 08, 2002 at 17:07 UTC
Use Hash Slices: `use Data::Dumper; my @usual = qw( data email stuff ); my @values = qw( 33 44 55 ); my %hash; @hash{ @usual } = @values; print Dumper \%hash;` [download] ----------------------------------------------------- Dr. Michael K. Neylon - mneylon-pm@masemware.com \|\| "You've left the lens cap of your mind on again, Pinky" - The Brain "I can see my house from here!" It's not what you know, but knowing how to find it if you don't know that's important	[reply] [d/l]
Re: Re: mapping two arrays into anon hash by agoth (Chaplain) on Jan 08, 2002 at 17:12 UTC
I know about hash slices !!, and am using one in the sub... I'm trying to slice anonymously without defining the hash explicitly, in order to build up a data structure with the minimum amount of effort.. looking for { username => 'fred' , @{}{@usual} fancyslice @values }; which led me to the @_{@ary1}; %_ monstrosity...	[reply]
Re: Re: Re: mapping two arrays into anon hash by Masem (Monsignor) on Jan 08, 2002 at 17:49 UTC
You're asking for the impossible, or if it is, it's going to be an ugly mess. Sure, it's nice to get a simple result that doesn't use extra variables, but if it becomes unreadible, then you're going to confuse others as to the meaning of your code. In this case, using a temporary hash is not going to increase your memory usage save for maybe an extra byte if you create a reference to the hash, and the code will be much easier to read. But here's another solution that doesn't use any extra variables beyond $_: `use Data::Dumper; my @names = qw ( web email stuff ); my @values = qw( 33 44 55 ); my $ref = { map { $names[$_] => $values[$_] } (0..$#names) }; print Dumper $ref;` [download] (It's still not as clean as using the hash slice, IMO, but if that's what you want...) ----------------------------------------------------- Dr. Michael K. Neylon - mneylon-pm@masemware.com \|\| "You've left the lens cap of your mind on again, Pinky" - The Brain "I can see my house from here!" It's not what you know, but knowing how to find it if you don't know that's important	[reply] [d/l]
Re: mapping two arrays into anon hash by agoth (Chaplain) on Jan 08, 2002 at 18:02 UTC
Re (tilly) 1: mapping two arrays into anon hash by tilly (Archbishop) on Jan 08, 2002 at 19:24 UTC
Take a look at tye's mapcar -- map for more than one list with which you can write (untested): `my %local = mapcar { @_ } \@keys, \@values;` [download]	[reply] [d/l]
Re: mapping two arrays into anon hash by jmcnamara (Monsignor) on Jan 08, 2002 at 17:22 UTC
You could use an array slice: `{ username => 'slice', ( @usual, 33, 44, 55 )[0, 3, 1, 4, 2, 5] },`I don't know if you could classify that as legible however. Personally, I'd prefer the subroutine approach for maintainability. -- John.	[reply] [d/l]


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