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Re: finding unique items in an array, from a text file

by andye (Curate)
on Jan 13, 2009 at 19:28 UTC ( #736054=note: print w/ replies, xml ) Need Help??


in reply to finding unique items in an array, from a text file

hiya - looks a bit overcomplicated, should be really simple. IMHO you don't need @lines, @uniq and %seen... only need one hash to do this.

I'd prefer to do something like this (off the top of my head, code not tested):

# open the file into FH my %uniq; $uniq{$_} = 1 while (<FH>); print join "\n", keys %uniq; # close the file

Hope that helps. All the best.


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Re^2: finding unique items in an array, from a text file
by johngg (Abbot) on Jan 13, 2009 at 23:27 UTC

    I think there might be a couple of problems with your code.

    • You join the output with \ns but you did not chomp the input so you will get extra blank lines.
    • Hash keys are unordered so the line order of the original file will be scrambled. This may or may not be an issue.

    The grep solutions suggested might be better if line order is to be preserved. Something like (again, not tested).

    ... my %seen = (); print grep ! $seen{ $_ } ++, <$fh>; ...

    Cheers,

    JohnGG

      All good points. ;)

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