Re: Difference arrays.

my @p = (1,1,1,1,1,2,2,2,3,3,4,5,6);
my @q = (1,2,3,4,5,6 );
# my @p = (43, 43, 44);
# my @q = (43, 43);

my %q;
$q{$_}++ for @q;

my @r = grep {
    --$q{$_} < 0;
} @p;

print join (',', @r), "\n";

[download]

Replies are listed 'Best First'.
Re^2: Difference arrays. by BrowserUk (Patriarch) on Sep 04, 2008 at 20:30 UTC
That's the one. I swear I tried that (at least twice!), but ... Many thanks++. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply]
Re^2: Difference arrays. by Skeeve (Parson) on Sep 04, 2008 at 19:36 UTC
Similar idea like mine above , but much, much better than I did it! ++ and ++ could I vote twice! `s$$([},&%#}/&/]+}%&{});#$&&s&&$^X.($'^"%]=\&(\|?{%` `+`.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e	[reply] [d/l] [select]
Re^2: Difference arrays. by journey (Monk) on Sep 06, 2008 at 02:34 UTC
My goodness it took me a while to get that one! Other slow brains like mine can have a look at this grep tutorial (where hashes are incremented): http://www.hidemail.de/blog/perl_tutor.shtml Also have a look a the PM node Re: How do I un-map this code?	[reply]
Re^2: Difference arrays. by Skeeve (Parson) on Sep 04, 2008 at 21:27 UTC
Big bug Just found it when I was examining kyle's solution. swap p and q and your routine will fail! Sorry! Not a bug! My mistake! `s$$([},&%#}/&/]+}%&{});#$&&s&&$^X.($'^"%]=\&(\|?{%` `+`.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e	[reply] [d/l] [select]
Re^3: Difference arrays. by betterworld (Curate) on Sep 04, 2008 at 21:35 UTC
I noticed that your solution is symmetric because it has the `abs` in it. However I was taking BrowserUk by the word: "those in the first not in the second". Given the restriction "one a proper subset of the other", it does not matter, and our solutions print essentially the same elements (maybe in a different order).	[reply] [d/l]
Re^4: Difference arrays. by Skeeve (Parson) on Sep 04, 2008 at 21:38 UTC
Something I learned again: Keep your big mouth shut until you read a second time ;-) So Sorry for crying too early. MINE has the bug. I've added comments above. `s$$([},&%#}/&/]+}%&{});#$&&s&&$^X.($'^"%]=\&(\|?{%` `+`.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e	[reply] [d/l] [select]

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