From: eggman2001 <sodani@...>
Date: 2011-05-02T12:37:49+09:00
Subject: Re: question about working with dates

This is very helpful. The only thing is that I'd like to use my
existing list of dates (for certain reasons) as opposed to creating a
new list.

My list includes only weekday dates, so I'm not concerned about
weekend/weekday so long as I'm using this list. I'd like to pull out
the first day of each month from my list. Any chance you could give me
an idea of how to do this?

Thanks much.

On Apr 30, 3:41 pm, 7stud -- <bbxx789_0...@yahoo.com> wrote:
> eggman2001 wrote in post #995956:
>
> > I have a list (in database) of weekday non-holiday dates that goes
> > from present back to 1990. From this list, I'd like to pull out dates
> > given different kinds of criteria and add them to an array. Examples
> > of criteria are:
> > - first day of the month for the most recent 5 years. Perhaps obvious,
> > but the first weekday non-holiday of the month isn't necessarily day 1
> > (i.e. 5/1).
>
> All it takes is a little math:
>
> require 'date'
>
> #Create array of all weekday dates for last five years
> #(probably faster than pulling them out of a database):
>
> date_arr = []
> previous_years = 5
>
> 1.upto(previous_years * 365) do |i|
>   new_date = today - i
>
>   next if [6,0].include?(new_date.wday)
>   date_arr << new_date
> end
>
> #Print out the first weekday of each month:
>
> date_arr.each do |date|
>   year = date.year
>   month = date.month
>   first_day_of_month = Date.new(year, month, 1)
>
>   while [6,0].include?(first_day_of_month.wday)
>     first_day_of_month += 1
>   end
>
>   if date == first_day_of_month
>     puts date
>   end
> end
>
> --output:--
> 2011-04-01
> 2011-03-01
> 2011-02-01
> 2011-01-03
> 2010-12-01
> 2010-11-01
> 2010-10-01
> 2010-09-01
> 2010-08-02
> 2010-07-01
> 2010-06-01
> 2010-05-03
> 2010-04-01
> 2010-03-01
> 2010-02-01
> 2010-01-01
> 2009-12-01
> 2009-11-02
> 2009-10-01
> 2009-09-01
> 2009-08-03
> 2009-07-01
> 2009-06-01
> 2009-05-01
> 2009-04-01
> 2009-03-02
> 2009-02-02
> 2009-01-01
> 2008-12-01
> 2008-11-03
> 2008-10-01
> 2008-09-01
> 2008-08-01
> 2008-07-01
> 2008-06-02
> 2008-05-01
> 2008-04-01
> 2008-03-03
> 2008-02-01
> 2008-01-01
> 2007-12-03
> 2007-11-01
> 2007-10-01
> 2007-09-03
> 2007-08-01
> 2007-07-02
> 2007-06-01
> 2007-05-01
> 2007-04-02
> 2007-03-01
> 2007-02-01
> 2007-01-01
> 2006-12-01
> 2006-11-01
> 2006-10-02
> 2006-09-01
> 2006-08-01
> 2006-07-03
> 2006-06-01
> 2006-05-01
>
> --
> Posted viahttp://www.ruby-forum.com/.