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Full Discussion: how to choose random columns
Top Forums Shell Programming and Scripting how to choose random columns Post 302516575 by kurumi on Sunday 24th of April 2011 08:31:58 AM
Old 04-24-2011
Ruby(1.9.1+)
Code:
f=open("file")
numcols=f.readline.split.size
cols=(1..numcols).to_a.sample(4)
while not f.eof?
    line=f.gets.split
    cols.each{|x| printf "%s " , line[x-1]}
    puts
end
f.close

This User Gave Thanks to kurumi For This Post:
 

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ERB(1)							 Ruby Programmers Reference Guide						    ERB(1)

NAME
erb -- Ruby Templating SYNOPSIS
erb [--version] [-UPdnvx] [-E ext[:int]] [-S level] [-T mode] [-r library] [--] [file ...] DESCRIPTION
erb is a command line front-end for ERB library, which is an implementation of eRuby. ERB provides an easy to use but powerful templating system for Ruby. Using ERB, actual Ruby code can be added to any plain text document for the purposes of generating document information details and/or flow control. erb is a part of Ruby. OPTIONS
--version Prints the version of erb. -E external[:internal] --encoding external[:internal] Specifies the default value(s) for external encodings and internal encoding. Values should be separated with colon (:). You can omit the one for internal encodings, then the value (Encoding.default_internal) will be nil. -P Evaluates lines starting with % as Ruby code and removes the tailing EOLs. -S level Specifies the safe level in which eRuby script will run. -T mode Specifies trim mode (default 0). mode can be one of 0 EOL remains after the embedded ruby script is evaluated. 1 EOL is removed if the line ends with %>. 2 EOL is removed if the line starts with <% and ends with %>. - EOL is removed if the line ends with -%>. And leading whitespaces are removed if the erb directive starts with <%-. -U can be one of Sets the default value for internal encodings (Encoding.default_internal) to UTF-8. -d --debug Turns on debug mode. $DEBUG will be set to true. -h --help Prints a summary of the options. -n Used with -x. Prepends the line number to each line in the output. -v Enables verbose mode. $VERBOSE will be set to true. -x Converts the eRuby script into Ruby script and prints it without line numbers. EXAMPLES
Here is an eRuby script <?xml version="1.0" ?> <% require 'prime' -%> <erb-example> <calc><%= 1+1 %></calc> <var><%= __FILE__ %></var> <library><%= Prime.each(10).to_a.join(", ") %></library> </erb-example> Command % erb -T - example.erb prints <?xml version="1.0" ?> <erb-example> <calc>2</calc> <var>example.erb</var> <library>2, 3, 5, 7</library> </erb-example> SEE ALSO
ruby(1). And see ri(1) documentation for ERB class. REPORTING BUGS
Security vulnerabilities should be reported via an email to <security@ruby-lang.org>. Reported problems will be published after being fixed. And you can report other bugs and feature requests via the Ruby Issue Tracking System (http://bugs.ruby-lang.org). Do not report security vulnerabilities via the system because it publishes the vulnerabilities immediately. AUTHORS
Written by Masatoshi SEKI. UNIX
November 7, 2012 UNIX
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