Every other week recurring event

I have the code for computing a weekly event:

(start_date..end_date).select{|d| d.wday == wday}

but I am wondering if anyone has any ideas for using this to figure out a recurring event for every other week. Is it possible to somehow specify every other within the .select method? Any other implementation ideas?

here's one way - not a one-liner, but not too complex:

start_date = DateTime.parse('2008-01-01') end_date = DateTime.parse('2008-04-01')

range = (start_date..end_date)

wday = 1 use_this = false every_other =

range.each do |date|   every_other << date if date.wday == wday && use_this   use_this = !use_this end

puts every_other.inspect