From: Josselin <josselin@...>
Date: 2006-10-19T15:01:59+09:00
Subject: Re: too complex for me...

On 2006-10-19 00:37:43 +0200, "Max Muermann" <ruby@muermann.org> said:

> On 10/19/06, Josselin <josselin@wanadoo.fr> wrote:
>> I need help from a ruby master... it's too hard with my present
>> understanding, any starting key will be apprciated ....
>> 
>> from a period range [start_date, end_date] in ayear ,  I need to
>> produce a list of special days like the following :
>> ["2006-10-12","2006-11-08"]  =>  { 10 :  [ 12 , 31], 11 : [ 1, 8] }
>> or
>> ["2006-10-12","2006-12-08"] =>  { 10 :  [ 12 , 31], 11 : [ 1, 30] , 12
>> : [ 1, 12] }
>> which means, for each month in the range
>>         the month number : [ period covered in the month] ,
>> 
>> where 'period covered in the month'  is
>>  [  1st day of the period or 1st day of the month , last day of the
>> period or last day of the month ]
>> 
>> coudl I get any clue ?
>> 
>> thanks a lot
>> 
>> joss
>> 
> 
> I had to make a change to the return values. They are now an array (to
> maintain order), with the first element being a string looking like
> "2006-10", as the code works for multiple dates, the second element is
> an array with the period covered.
> 
> Lots of special case code for handling year boundaries. I'm sure this
> can be tightened up, I'd be interested to hear views as to how...
> 
> require 'date'
> 
> def coverage rg
>   from = Date.parse(rg[0])
>   to = Date.parse(rg[1])
> 
>   cover = []
> 
>   # build a list of all month indexes we need to iterate over
>   if from.year==to.year
>     # trivial case, both dates fall within the same year
>     month_range = (from.month..to.month )
>   else
>     # complex case - dates in different years
> 
>     # first year - form month to december
>     month_range = (from.month..12).to_a
> 
>     # more than one year covered?
>     (to.year-from.year-1).times do |year|
>       # jan to dec
>       month_range += (1..12).to_a
>     end
>     # last year - jan to to.month
>     month_range += (1..to.month).to_a
>   end
> 
>   y = from.year
> 
>   month_range.each do |m|
>     if from < Date.new(y,m,1)
>       first_day = 1
>     else
>       first_day = from.day
>     end
> 
>     # passing -1 as the day gets the last day of the month
>     end_of_month = Date.new(y,m,-1)
> 
>     if to > end_of_month
>       last_day = end_of_month.day
>     else
>       last_day = to.day
>     end
> 
>     cover << ["#{y}-#{m}",[first_day, last_day]]
> 
>     # next year?
>     y +=1 if m==12
>   end
>   cover
> end
> 
> p coverage(["2006-10-12","2008-02-12"])
> 
> Cheers,
> Max

Thanks a lot I'll work on it today...

joss