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How do I select a random line from a file?

by faq_monk (Initiate)
on Oct 13, 1999 at 03:42 UTC ( #820=perlfaq nodetype: print w/replies, xml ) Need Help??

Current Perl documentation can be found at perldoc.perl.org.

Here is our local, out-dated (pre-5.6) version:

Here's an algorithm from the Camel Book:

    srand;
    rand($.) < 1 && ($line = $_) while <>;

This has a significant advantage in space over reading the whole file in. A simple proof by induction is available upon request if you doubt its correctness.

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[Discipulus]: who make the invitation? the program?!?
[choroba]: it's historical
[erix]: pull requests
[choroba]: originally, you sent a pull request to someone by email, i.e. you asked them to pull from your repo
[Discipulus]: if is the author of a patch, is more like a 'request to push' into rather than a pull request..
[choroba]: as it's considered unpolite to push to someone else's repo
[choroba]: and in fact, you don't push into the target repo, you push into your branch of your fork
[choroba]: the maintainer of the upstream repo than "merges" the pull request, i.e. they pull from your fork into the upstream
[Discipulus]: ' i.e. you asked them to pull from your repo' =~ I (subj) want to push
[Discipulus]: chorobayour words are reasonable

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