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Re: reading lines into an array

by BrowserUk (Pope)
on Jun 11, 2013 at 03:42 UTC ( #1038188=note: print w/ replies, xml ) Need Help??


in reply to reading lines into an array

If performance is in any way a criteria, don't use File::Slurp. And if the size of the file is any more than a few hundred lines, don't use list assignment either:

#! perl -slw use strict; use File::Slurp; use Benchmark qw[ cmpthese ]; print `wc -l $ARGV[ 0 ]`; open our $infile, '<', $ARGV[ 0 ] or die $!; our $I //= -1; cmpthese $I, { a=> q[ sysseek $infile, 0, 0; my @lines = read_file( $infile, chomp => 1 ); print 'a: ', scalar @lines if $I == 1; ], b=> q[ sysseek $infile, 0, 0; chomp( my @lines = <$infile> ); print 'b: ', scalar @lines if $I == 1; ], c=> q[ sysseek $infile, 0, 0; my @lines; $lines[ @lines ] = <$infile> until eof $infile; chomp @lines; print 'c: ', scalar @lines if $I == 1; ], }; __END__ C:\test>t-slurp -I=1 small.tsv 1000000 small.tsv a: 1000000 (warning: too few iterations for a reliable count) b: 1000000 (warning: too few iterations for a reliable count) c: 1000000 (warning: too few iterations for a reliable count) s/iter a b c a 257 -- -98% -98% b 4.94 5115% -- -16% c 4.14 6119% 19% -- C:\test>t-slurp -I=-1 small.tsv 1000000 small.tsv (warning: too few iterations for a reliable count) (warning: too few iterations for a reliable count) s/iter b a c b 4.88 -- -4% -100% a 4.69 4% -- -100% c 1.39e-006 350525381% 337007680% --

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Re^2: reading lines into an array
by fionbarr (Pilgrim) on Jun 11, 2013 at 12:29 UTC
    thanks all; thoughtful replies.

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