Display a sparkline live, based on the STDIN (newline-seperated) or a comma-seperated list on the cmd-line. Options are obvious enough.

gistfile1.rb

#!/usr/bin/env ruby
# encoding: UTF-8
# live sparkline display
# gems required: ruby-terminfo, getoptions

require 'terminfo'
require 'getoptions'

def bar_height n, min, max
  h = (((n - min) / (max - min)) * $bs).to_i
  h = 0 if h < 0; h = $bs if h > $bs;
  return h
end

def show_bar h
  b = $bars[h]
  $bar.prepend b
  
  ww = TermInfo.screen_size[1]
  print "\r#{$bar[0..ww-1]}"
  $stdout.flush
end

$bars = %w{▂ ▃ ▄ ▅ ▆ ▇}; $bs = $bars.length-1
$o = GetOptions.new %w{min|l:f max|u:f sep|f:s}
$bar = ""

sep = $o[:sep] || $/
min = $o[:min] || 0
max = $o[:max] || $bs

if ARGV[0]
  sep = ',' unless $o[:sep]
  ns = ARGV[0].split(sep).map(&:to_f)
  min, max = ns.min, ns.max
  hs = ns.map {|n| bar_height n, min, max}
  hs.each {|h| show_bar h}; puts
else
  trap("SIGINT") { exit 0 }
  while gets sep
    n = $_.to_f
    h = bar_height n, min, max
    show_bar h
  end
end