Iterating between two DateTimes, with a one hour step

Question

I'm looking for an efficient way, in Ruby 1.9.x/Rails 3.2.x, to iterate between two DateTime objects, with a one-hour step.

('2013-01-01'.to_datetime .. '2013-02-01'.to_datetime).step(1.hour) do |date|    ... end 

I understand that an issue with this is that 1.hour is just the number of seconds, but my attempts to convert that to a DateTime object and use that as the step doesn't work either.

I looked at "Beware of Ruby Sugar". It mentions, near the bottom, that DateTime has a direct step method. I confirmed this by running methods on a DateTime object, but I cannot find any documentation on step in DateTime, in either Ruby's or Rails' documents.

Answer 1

Similar to my answer in "How do I return an array of days and hours from a range?", the trick is to use to_i to work with seconds since the epoch:

('2013-01-01'.to_datetime.to_i .. '2013-02-01'.to_datetime.to_i).step(1.hour) do |date|   puts Time.at(date) end 

Note that Time.at() converts using your local time zone, so you may want to specify UTC by using Time.at(date).utc

Answer 2

Maybe late but, you can do it without Rails, for example to step with hours:

Ruby 2.1.0

require 'time'   hour_step = (1.to_f/24)  date_time = DateTime.new(2015,4,1,00,00) date_time_limit = DateTime.new(2015,4,1,6,00)  date_time.step(date_time_limit,hour_step).each{|e| puts e}  2015-04-01T00:00:00+00:00 2015-04-01T01:00:00+00:00 2015-04-01T02:00:00+00:00 2015-04-01T03:00:00+00:00 2015-04-01T04:00:00+00:00 2015-04-01T05:00:00+00:00 2015-04-01T06:00:00+00:00 

Or minutes:

#one_minute_step = (1.to_f/24/60)  fifteen_minutes_step = (1.to_f/24/4)  date_time = DateTime.new(2015,4,1,00,00) date_time_limit = DateTime.new(2015,4,1,00,59)  date_time.step(date_time_limit,fifteen_minutes_step).each{|e| puts e}  2015-04-01T00:00:00+00:00 2015-04-01T00:15:00+00:00 2015-04-01T00:30:00+00:00 2015-04-01T00:45:00+00:00 

I hope it helps.