simple iostats in ruby

iostats.rb

def read_file
  File.open('/proc/diskstats').collect do |line|
    entries = line.split
    next unless entries[2] =~/sda/
    [entries[2],entries[4],entries[5]]
  end.compact.flatten
end

while true
  time_1 = Time.now.to_f
  arr1 = read_file
  sleep 1
  arr2 = read_file
  time_2 = Time.now.to_f
  delta_time = time_2 - time_1
  puts "#{arr1[0]}\tread: #{(arr2[1].to_f - arr1[1].to_f) / delta_time} bytes/sec\twrite: #{(arr2[2].to_f - arr2[1].to_f)/delta_time} bytes/sec"
end