Beefy Boxes and Bandwidth Generously Provided by pair Networks
Welcome to the Monastery
 
PerlMonks  

Re: Fast, Efficient Union and Intersection on arrays

by Roy Johnson (Monsignor)
on Nov 20, 2008 at 18:07 UTC ( #724942=note: print w/ replies, xml ) Need Help??


in reply to Fast, Efficient Union and Intersection on arrays

I note two things: you only want the number of elements in the intersection and union, not the actual intersection and union; and your method suggests that there are no duplicates in the sets. So you don't need to find the union, explicitly. It is just the total number in I + J, minus the intersection.

sub get_int_uni2 { my ($in, $jn) = @_; my %i; @i{@$in} = (); my $int = grep exists $i{$_}, @$jn; return ($int, @$in + @$jn - $int); }
Sadly, I don't see any real improvement in performance (thanks to BrowserUK for the benchmarkery).

Caution: Contents may have been coded under pressure.


Comment on Re: Fast, Efficient Union and Intersection on arrays
Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://724942]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others drinking their drinks and smoking their pipes about the Monastery: (11)
As of 2015-07-28 11:04 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (254 votes), past polls