Calculating the number of weeks in a year with Ruby

Question

Is there a way in Ruby to calculate the number of weeks(ISO 8601) for a given year? I\'m currently using a lookup table and I\'d like to stop using it.

Answer 1

require 'date'
def num_weeks(year = Date.today.year)
  # all years starting with Thursday, and leap years starting with Wednesday have 53 weeks
  # http://en.wikipedia.org/wiki/ISO_week_date#Last_week
  d = Date.new(year, 1, 1)
  return 53 if d.wday == 4
  return 53 if d.leap? and d.wday == 3
  52
end