Beefy Boxes and Bandwidth Generously Provided by pair Networks
Come for the quick hacks, stay for the epiphanies.
 
PerlMonks  

Re: Generating Repeatable Pseudorandom Sequences

by Abigail-II (Bishop)
on Sep 05, 2002 at 16:51 UTC ( [id://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

Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Node Status?
node history
Node Type: note [id://195439]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others learning in the Monastery: (2)
As of 2024-04-26 00:31 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found