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Re^2: Grab 3 lines before and 2 after each regex hit (sliding window)

by LanX (Bishop)
on Apr 25, 2014 at 20:31 UTC ( #1083855=note: print w/replies, xml ) Need Help??


in reply to Re: Grab 3 lines before and 2 after each regex hit
in thread Grab 3 lines before and 2 after each regex hit

> This is a fairly primitive way to do it:

using a sliding window (safer with huge streams)

use strict; use warnings; use Data::Dump; my @window; push @window, scalar <DATA> for 1..5; # init while (my $line = <DATA>) { push @window, $line; chomp @window; if( $window[3] =~ m/[^\d]+\d+/ ){ dd \@window; } shift @window; } __END__ alpha beta something a07607 b-alpha b-beta b-something b-something else c-alpha c-beta c-somethin a9706 d-alpha d-beta d-something d-something else
-->
["alpha", "beta", "something", "a07607", "b-alpha", "b-beta"] ["c-alpha", "c-beta", "c-somethin", "a9706", "d-alpha", "d-beta"]

Cheers Rolf

( addicted to the Perl Programming Language)

update

maybe more elegant

use strict; use warnings; use Data::Dump; my @window; while (my $line = <DATA>) { push @window, $line; next if @window < 6; # init if( $window[3] =~ m/[^\d]+\d+/ ){ dd \@window; } shift @window; }

Update

Oh the latter (more elegant) approach has a clear advantage, if you want to avoid overlapping results you just need to empty the window after a match and it gets automatically refilled. :)

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Re^3: Grab 3 lines before and 2 after each regex hit (sliding window)
by HarryPutnam (Novice) on Apr 25, 2014 at 21:48 UTC
    The sliding window sounds like another great suggestion

    Thank you.

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