in reply to Re^3: Best method to diff large array
in thread Best method to diff very large array efficiently

Hi there,

I updated the post based on your questions, to answer your question, the values are unique and its an INT data type

Thanks,

AJ

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Re^5: Best method to diff large array
by BrowserUk (Patriarch) on Nov 25, 2013 at 06:24 UTC

    For integers, this will beat using hashes hands-down: 

    @a1 = map int( rand 1e6 ), 1 .. 8000; 
@a2 = map int( rand 1e6 ), 1 .. 6000;;

vec( $vec, $_, 1 )=1 for @a2;;

@missingFromA2 = grep !vec( $vec, $_, 1 ), @a1;;

    [download]

    A note of caution, if the integers can be bigger than say 2**30, then this won't work properly on older perls; and would consume large amounts of memory on newer perls. But if your integers are less than that, it is very, very fast.

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[d/l]

      Waooo, this is really excellent, thank you for sharing.

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