| # hll-err.rb - Copyright (C) 2014 Salvatore Sanfilippo | |
| # BSD license, See the COPYING file for more information. | |
| # | |
| # Check error of HyperLogLog Redis implementation for different set sizes. | |
| require 'rubygems' | |
| require 'redis' | |
| require 'digest/sha1' | |
| r = Redis.new | |
| r.del('hll') | |
| i = 0 | |
| while true do | |
| 100.times { | |
| elements = [] | |
| 1000.times { | |
| ele = Digest::SHA1.hexdigest(i.to_s) | |
| elements << ele | |
| i += 1 | |
| } | |
| r.pfadd('hll',elements) | |
| } | |
| approx = r.pfcount('hll') | |
| abs_err = (approx-i).abs | |
| rel_err = 100.to_f*abs_err/i | |
| puts "#{i} vs #{approx}: #{rel_err}%" | |
| end | |