XKCD progress indicator

You all read today’s xkcd and wanted to incorporate this formula into your programs straight away.

Here’s my Ruby implementation, if you would like a quick fix:

require 'date'

class XkcdDate

  # Progress indicator formatted as a date, as in http://xkcd.com/1017/
  def self.progress(amount, total)
    percent = (amount.to_f / total.to_f)
    years = Math::E ** (20.3444 * percent ** 3 + 3) - Math::E ** 3
    Date.today - (years * 365.25)
  end

end

It takes two arguments (amount and total, used to form the ratio) and returns a Ruby Date object, which you can format any way you like.

And examples of its uses, as in the comic:

>> [7.308, 31.12, 47.91, 70.33, 90.42, 100].each {|p| puts "#{p}: #{XkcdDate.progress(p, 100)}"}
7.308: 2011-12-18
31.12: 1995-02-15
47.91: 1844-01-17
70.33: -21765-11-11
90.42: -68315229-02-11
100: -13751308941-03-30
=> [7.308, 31.12, 47.91, 70.33, 90.42, 100]

For those implementing it in other languages, when Randall says “percentage” he actually means “ratio”.

Posted by on Feb 15, 2012 in Tech | 0 comments

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