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Top Forums UNIX for Dummies Questions & Answers How to randomly select lines from a text file Post 302720475 by drl on Wednesday 24th of October 2012 09:00:25 AM
Old 10-24-2012
Hi.

There are a number of commonly-available utilities to do this. Here is a demonstration of two:
Code:
#!/usr/bin/env bash

# @(#) s1	Demonstrate random selection of lines with rl, shuf.

pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C rl shuf

pl " Lines selected from:"
cat data0

# Prepare data file from single line of words.
tr ' ' '\n' < data0 > data1

pl " Results from shuf, 1:"
shuf -n 3 data1

pl " Results from shuf, 2:"
shuf -n 3 data1

pl " Results from rl, 1:"
rl -c 3 data1

pl " Results from rl, 2:"
rl -c 3 data1

exit 0

producing:
Code:
% ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0.8 (lenny) 
bash GNU bash 3.2.39
rl 0.2.7
shuf (GNU coreutils) 6.10

-----
 Lines selected from:
foo bar baz qux quux corge grault garble warg fred plugh xyzzy thud

-----
 Results from shuf, 1:
quux
thud
qux

-----
 Results from shuf, 2:
thud
xyzzy
quux

-----
 Results from rl, 1:
corge
qux
grault

-----
 Results from rl, 2:
thud
corge
warg

You may need to install these from your distribution repository. See man pages for details.

See also Algorithm::Numerical::Sample - search.cpan.org if a perl module is desirable.

Best wishes ... cheers, drl
This User Gave Thanks to drl For This Post:
 

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MIME::Parser::Results(3)				User Contributed Perl Documentation				  MIME::Parser::Results(3)

NAME
MIME::Parser::Results - results of the last entity parsed SYNOPSIS
Before reading further, you should see MIME::Parser to make sure that you understand where this module fits into the grand scheme of things. Go on, do it now. I'll wait. Ready? Ok... ### Do parse, get results: my $entity = eval { $parser->parse(*STDIN); }; my $results = $parser->results; ### Get all messages logged: @msgs = $results->msgs; ### Get messages of specific types (also tests if there were problems): $had_errors = $results->errors; $had_warnings = $results->warnings; ### Get outermost header: $top_head = $results->top_head; DESCRIPTION
Results from the last MIME::Parser parse. PUBLIC INTERFACE
new Constructor. msgs Instance method. Return all messages that we logged, in order. Every message is a string beginning with its type followed by ": "; the current types are "debug", "warning", and "error". errors Instance method. Return all error messages that we logged, in order. A convenience front-end onto msgs(). warnings Instance method. Return all warning messages that we logged, in order. A convenience front-end onto msgs(). top_head Instance method. Return the topmost header, if we were able to read it. This may be useful if the parse fails. SEE ALSO
MIME::Tools, MIME::Parser AUTHOR
Eryq (eryq@zeegee.com), ZeeGee Software Inc (http://www.zeegee.com). All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.18.2 2008-06-30 MIME::Parser::Results(3)
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