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Picking a Random Line from a File
CodeExpectedActual
module Enumerable
  def random_line
    selected = nil
    each_with_index { |line, lineno| selected = line if rand < 1.0/lineno }    
    return selected.chomp if selected
  end
end
#Create a file with 1000 lines
open('random_line_test', 'w') do |f| 
  1000.times { |i| f.puts "Line #{i}" }
end
#Pick random lines from the file.
f = open('random_line_test')
f.random_line
 "Line 520" "Line 520" 
f.random_line
 nil nil 
f.rewind
f.random_line
 "Line 727" "Line 727" 
File.open('random_line_test') do |f|
  l = f.readlines
  l[rand(l.size)].chomp
end
 "Line 708" "Line 708"