# Commercial Calendar Calculations **URL:** \ **Category:** Ruby\ **Created:** [June 3, 2008, 9:47pm UTC](https://www.ruby-forum.com/t/commercial-calendar-calculations/139431 "2008-06-03T21:47:27Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![sjames](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/c57346/32.png) [@sjames](https://www.ruby-forum.com/u/sjames)\ **Post date:** [June 3, 2008, 9:47pm UTC](https://www.ruby-forum.com/t/commercial-calendar-calculations/139431/1 "2008-06-03T21:47:27Z")
I’m interested in doing calculations with a commercial calendar. For example, “Find every 2nd business day of the month for 2008”. I’m feeling a little long on how to approach the topic. Does anyone know of a library I could leverage for such a thing (the ability to use said library in Rails is a must)? If not, does anyone have experience that they could share on the matter? Many thanks, James H. ---
**Author:** ![sjames](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/c57346/32.png) [@sjames](https://www.ruby-forum.com/u/sjames)\ **Post date:** [June 3, 2008, 10:37pm UTC](https://www.ruby-forum.com/t/commercial-calendar-calculations/139431/2 "2008-06-03T22:37:31Z")
On Tue, Jun 3, 2008 at 2:43 PM, James H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I’m interested in doing calculations with a commercial calendar. For > example, “Find every 2nd business day of the month for 2008”. I’m feeling a > little long on how to approach the topic. Does anyone know of a library I > could leverage for such a thing (the ability to use said library in Rails is > a must)? If not, does anyone have experience that they could share on the > matter? The runt gem provides a nice library for working with recurring events, it’s probably got what you’re looking for. Personally, I looked at runt for an event calendar I built sometime last year, but it didn’t end up being useful as I needed to be able to store the events in a relational database and query for matching events therein. To use runt, I’d have had to hydrate all of the events whenever I wanted to run a query. That was too slow for my use case, so I ended up doing it all in sql. I’ll be happy to share the details of that implementation if you’re in a similar boat. - donald ---
**Author:** ![sjames](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/c57346/32.png) [@sjames](https://www.ruby-forum.com/u/sjames)\ **Post date:** [June 4, 2008, 12:40am UTC](https://www.ruby-forum.com/t/commercial-calendar-calculations/139431/3 "2008-06-04T00:40:45Z")
On Jun 3, 3:43 pm, James H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I’m interested in doing calculations with a commercial calendar. For > example, “Find every 2nd business day of the month for 2008”. I’m feeling a > little long on how to approach the topic. Does anyone know of a library I > could leverage for such a thing (the ability to use said library in Rails is > a must)? If not, does anyone have experience that they could share on the > matter? When you say “2nd business day”, do you mean logic like, “the 2nd of the month if it’s Tuesday-Friday or the first Monday of the month otherwise”? Or do you want to take into account a list of holidays that might make certain weekdays not count as business days? If it’s the former, you could use the Date class (in the ‘date’ library). I don’t know of a library that handles issues such as holidays; have you’ve combed through [rubyforge.org](http://rubyforge.org)? Eric ==== [LearnRuby.com](http://LearnRuby.com) offers Rails & Ruby HANDS-ON public & ON-SITE workshops. Ruby Fundamentals Wkshp June 16-18 Ann Arbor, Mich. Ready for Rails R. Wkshp June 23-24 Ann Arbor, Mich. Ruby on Rails Wkshp June 25-27 Ann Arbor, Mich. Ruby Plus Rails Combo Wkshp June 23-27 Ann Arbor, Mich Please visit [http://LearnRuby.com](http://LearnRuby.com) for all the details. ---
**Author:** ![sjames](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/c57346/32.png) [@sjames](https://www.ruby-forum.com/u/sjames)\ **Post date:** [June 4, 2008, 3:05am UTC](https://www.ruby-forum.com/t/commercial-calendar-calculations/139431/4 "2008-06-04T03:05:25Z")
Eric, Both. So, if you ask the program to schedule “every first Friday of the month”, if Friday is a holiday, the program should schedule a Thursday (likewise, if you say “every last day of the month”, if the last day is a holiday, the first business day prior would be scheduled). It’s quite a complicated situation. I thought Runt (as Donald mentioned) might help, but I’m not sure it will. James ---
**Author:** ![sjames](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/c57346/32.png) [@sjames](https://www.ruby-forum.com/u/sjames)\ **Post date:** [June 4, 2008, 3:00am UTC](https://www.ruby-forum.com/t/commercial-calendar-calculations/139431/5 "2008-06-04T03:00:42Z")
Donald, I’m definitely interested in hearing about the details. I’ll be having to deal with an RDBMS as well. James ---
**Author:** ![sjames](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/c57346/32.png) [@sjames](https://www.ruby-forum.com/u/sjames)\ **Post date:** [June 4, 2008, 6:07am UTC](https://www.ruby-forum.com/t/commercial-calendar-calculations/139431/6 "2008-06-04T06:07:22Z")
you could try something like this…very rough pseudo code, but the logic should be there def checkworkday(datechecked) day = datechecked while day == holiday && day == dayoff day = nextday end return day; end dayneeded=firstdayofmonth nomberofworkdays.times {dayneeded = checkworkday(dayneeded)} xdayofworkthismonth = dayneeded ---
**Author:** ![sjames](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/c57346/32.png) [@sjames](https://www.ruby-forum.com/u/sjames)\ **Post date:** [June 4, 2008, 6:33pm UTC](https://www.ruby-forum.com/t/commercial-calendar-calculations/139431/7 "2008-06-04T18:33:09Z")
Oh, I see! So if you wanted to get the Date object corresponding to a row you’d just dump those values into Date.civil. Smart! I’m curious about your occurrences table. I think I understand this to be one-time-only events. Is that correct? James ---
**Author:** ![sjames](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/c57346/32.png) [@sjames](https://www.ruby-forum.com/u/sjames)\ **Post date:** [June 4, 2008, 5:08pm UTC](https://www.ruby-forum.com/t/commercial-calendar-calculations/139431/8 "2008-06-04T17:08:46Z")
On Tue, Jun 3, 2008 at 7:59 PM, James H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Donald, > I’m definitely interested in hearing about the details. I’ll be having to > deal with an RDBMS as well. Sure thing, I’ll describe briefly here and you can feel free to email me if you have further questions. My data model included a table of events, a table of occurrences for events on specific dates, and a table of recurrences for events that recur. The recurrences table has columns for event id, weekday, monthweek, and monthday; an event occurring on all Mondays would have 1 for weekday and null for the others, while an event occurring on the last Friday of a month would have 5 for the weekday and -1 for the monthweek. I created a view joining these data (events, occurrences, recurrences) against a table of dates, excluding holidays, and end up with a virtual table consisting of a row for every valid event-date pair. Given that the date functions in SQL aren’t standardized, I’d thought this would have been practically difficult to bundle up as a rails plugin, but it now occurs to me that I could store the date parts (e.g. weekday) in the table of dates, eliminating the need for any date functions in the database. I may give that a whirl this weekend. - donald