Re: Union of arrays

You already have correct answers. I like to do it like this:

my (%hsh, @union_arr);
@hsh{@arr_in_1, @arr_in_2} = ();
@union_arr = keys %hsh;
[download]

After Compline,
Zaxo

Comment on Re: Union of arrays Download Code

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Re: Re: Union of arrays by thpfft (Chaplain) on Oct 26, 2002 at 12:06 UTC
The hash slice is very neat, but you're going to lose sequence that way, which might matter. How about a nearly-one-liner: `my %seen; my @union = grep { not $seen{$_}++ } (@arr_in_1, @arr_in_2);` [download] which also skips duplicates in the existing arrays, as yours would. Btw, does the hash slice - if, indeed, that's what it is - cut out this loop altogether, or does it just conceal it? If the former then I imagine this approach is a lot less efficient. ananda: the perl cookbook deals with this kind of question very well, iirc. update: code tweak	[reply] [d/l]

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Re: Re: Union of arrays
by thpfft (Chaplain) on Oct 26, 2002 at 12:06 UTC

The hash slice is very neat, but you're going to lose sequence that way, which might matter. How about a nearly-one-liner:

my %seen;
my @union = grep { not $seen{$_}++ } (@arr_in_1, @arr_in_2);
[download]

which also skips duplicates in the existing arrays, as yours would.

Btw, does the hash slice - if, indeed, that's what it is - cut out this loop altogether, or does it just conceal it? If the former then I imagine this approach is a lot less efficient.

ananda: the perl cookbook deals with this kind of question very well, iirc.

update: code tweak

[reply]
[d/l]