Re: Re: Re: Re: Optimizing quickly hash tables by checking multiple conditions

my %newhash =                           
              map  { $_ => $refdes_bom{$_} }  
              grep {     CPN($refdes_bom{$_}) 
                     and ITEM($refdes_bom{$_}) }
              keys %refdes_bom;
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I have tried to make that basic routine you gave me work but failed as it will not process the keywords bar and foo. The error message I get is :

Undefined subroutine &main::CPN called at compal_test.pl line 37.

Am I missing the obvious basics here ?

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Re: Re: Re: Re: Re: Optimizing quickly hash tables by checking multiple conditions by revdiablo (Prior) on May 06, 2004 at 04:50 UTC
What is in your `CPN` and `ITEM` subroutines? You have to define them to check for criteria you want. They don't just magically appear out of nowhere. Here is a fully-functional example, hopefully it will make something click for you: `my %hash = ( first => { a => 2, b => 3 }, second => { a => 3, b => 2 }, third => { a => 5, b => 4 }, fourth => { a => 4, b => 6 }, ); my %newhash = map { $_ => $hash{$_} } grep { foo($hash{$_}) and bar($hash{$_}) } keys %hash; print "$_\n" foreach keys %newhash; sub foo { my ($href) = @_; $href->{a} > 3; } sub bar { my ($href) = @_; $href->{b} > 2; }` [download] As you can see, in this example `foo` makes sure the value at `a` is greater than 3, and `bar` makes sure the value at `b` is greater than 2. The end result should print `third` and `fourth`, since those are the only keys that pass the criteria.	[reply] [d/l] [select]

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Re: Re: Re: Re: Re: Optimizing quickly hash tables by checking multiple conditions
by revdiablo (Prior) on May 06, 2004 at 04:50 UTC

What is in your CPN and ITEM subroutines? You have to define them to check for criteria you want. They don't just magically appear out of nowhere. Here is a fully-functional example, hopefully it will make something click for you:

my %hash = (
    first  => { a => 2, b => 3 },
    second => { a => 3, b => 2 },
    third  => { a => 5, b => 4 },
    fourth => { a => 4, b => 6 },
);

my %newhash = map  { $_ => $hash{$_} }
              grep {     foo($hash{$_})
                     and bar($hash{$_}) }
              keys %hash;

print "$_\n" foreach keys %newhash;

sub foo {
    my ($href) = @_;
    $href->{a} > 3;
}

sub bar {
    my ($href) = @_;
    $href->{b} > 2;
}
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As you can see, in this example foo makes sure the value at a is greater than 3, and bar makes sure the value at b is greater than 2. The end result should print third and fourth, since those are the only keys that pass the criteria.

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