in reply to Re: Hash slices
in thread Hash slices

I tried to find an elegant way to avoid map...grep, but only came up with this: 
my %hash2;
map { $hash2{$_} = $hash{$_} if /^NETWORK/ } keys %hash;

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which is fancy-looking, non-map-in-a-void-context way of saying: 
my %hash2;
{ $hash2{$_} = $hash{$_} if /^NETWORK/ } foreach keys %hash;

[download]
My rough check with Benchmark shows no difference between map...grep and map alone until the hash sizes were increased to force memory paging to disk.

[I didn't check to see if anything was optimized away.]

-QM
--
Quantum Mechanics: The dreams stuff is made of

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Re: Re: Re: Hash slices
by revdiablo (Prior) on Feb 17, 2004 at 22:28 UTC
    I tried to find an elegant way to avoid map...grep

    Roger's first solution actually does this in a pretty nice way. I added some formatting to [hopefully] make it more clear, but here's his code:

        my %hashslice1 = map { /^NETWORK/
                           ? ($_, $hash{$_})
                           : (             )
                         } keys %hash;

    [download]

    Even still, I can see how mixing the selection of the keys with the hashification is a bit confusing, so that's why I gave a map {} grep {} solution that separates them.

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[d/l]
[select]
      Thanks!

      Need new glasses (or new eyes).

      -QM
      --
      Quantum Mechanics: The dreams stuff is made of

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