FAQ 5.37 How do I select a random line from a file?
- From: PerlFAQ Server <comdog@xxxxxxxxx>
- Date: Thu, 30 Jun 2005 16:03:00 +0000 (UTC)
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5.37: How do I select a random line from a file?
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. You can find a proof of this method in *The Art of Computer
Programming*, Volume 2, Section 3.4.2, by Donald E. Knuth.
You can use the File::Random module which provides a function for that
algorithm:
use File::Random qw/random_line/;
my $line = random_line($filename);
Another way is to use the Tie::File module, which treats the entire file
as an array. Simply access a random array element.
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