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Re: Generating Repeatable Pseudorandom Sequences

by Abigail-II (Bishop)
on Sep 05, 2002 at 16:51 UTC ( #195439=note: print w/replies, xml ) Need Help??


in reply to Generating Repeatable Pseudorandom Sequences

Calling srand more than once is not recommended, but that doesn't mean the results are always bad. It depends a bit on the needs of the rest of the program, but you might be able to call srand with a known seed just before you sort, and after the sort, you call srand without an argument.

But there's a totally different approach. If you need to shuffle an array using the same permutation multiple times, instead of playing games by seeding a PRN generator with the same seed, you could just shuffle the numbers 0 .. $#array and remember them (say, in an array @perm_indices). Then, if you need to shuffle an array again, you do:

@shuffled = @array [@perm_indices];

You may be able to use the Memoize module to this storing for you.

Abigail

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