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Commercial Calendar Calculations

James Herdman

6/3/2008 7:44:00 PM

[Note: parts of this message were removed to make it a legal post.]

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.
7 Answers

Donald Ball

6/3/2008 8:34:00 PM

0

On Tue, Jun 3, 2008 at 2:43 PM, James Herdman <james.herdman@gmail.com> 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

Eric I.

6/3/2008 10:36:00 PM

0

On Jun 3, 3:43 pm, James Herdman <james.herd...@gmail.com> 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?

Eric

====

LearnRuby.com offers Rails & Ruby HANDS-ON public & ON-SITE
workshops.
Ruby Fundamentals Wkshp June 16-18 Ann Arbor, Mich.
Ready for Rails Ruby 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://Lea... for all the details.

James Herdman

6/4/2008 12:59:00 AM

0

[Note: parts of this message were removed to make it a legal post.]

Donald,
I'm definitely interested in hearing about the details. I'll be having to
deal with an RDBMS as well.

James

On Tue, Jun 3, 2008 at 4:34 PM, Donald Ball <donald.ball@gmail.com> wrote:

> On Tue, Jun 3, 2008 at 2:43 PM, James Herdman <james.herdman@gmail.com>
> 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
>
>

James Herdman

6/4/2008 1:04:00 AM

0

[Note: parts of this message were removed to make it a legal post.]

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

On Tue, Jun 3, 2008 at 6:39 PM, Eric I. <rubytraining@gmail.com> wrote:

> On Jun 3, 3:43 pm, James Herdman <james.herd...@gmail.com> 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?
>
> Eric
>
> ====
>
> LearnRuby.com offers Rails & Ruby HANDS-ON public & ON-SITE
> workshops.
> Ruby Fundamentals Wkshp June 16-18 Ann Arbor, Mich.
> Ready for Rails Ruby 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://Lea... for all the details.
>
>

`brad`

6/4/2008 4:03:00 AM

0

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

Donald Ball

6/4/2008 3:07:00 PM

0

On Tue, Jun 3, 2008 at 7:59 PM, James Herdman <james.herdman@gmail.com> 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

James Herdman

6/4/2008 4:32:00 PM

0

[Note: parts of this message were removed to make it a legal post.]

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

On Wed, Jun 4, 2008 at 11:07 AM, Donald Ball <donald.ball@gmail.com> wrote:

> On Tue, Jun 3, 2008 at 7:59 PM, James Herdman <james.herdman@gmail.com>
> 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
>
>