From: Ken Bloom <kbloom@...>
Date: 2007-10-24T23:10:21+09:00
Subject: Re: [QUIZ] Time Window (#144)

On Wed, 24 Oct 2007 10:04:56 +0900, James Koppel wrote:

> Here's my solution. It converts a time window into an array of arrays of
> ranges. Each range matches an interval of time (e.g.: 500..1700); each
> subarray contains all the ranges for a given day. I then wrote the
> simple Array#some method that returns true if the given predicate
> returns true for at least one of its elements, which I used to write
> TimeWindow#incude?.
> 
> $days = {"Sun"=>0,
>               "Mon"=>1,
>               "Tue"=>2,
>               "Wed"=>3,
>               "Thu"=>4,
>               "Fri"=>5,
>               "Sat"=>6}

I suggest using a constant rather than a global variable for this. You 
can put the constant in the TimeWindow class.

> class Array
>   def some
>     each {|el| return true if yield el}
>     false
>   end
> end

This has already been discussed as being equal to Enumerable#any?

> class TimeWindow
>   def initialize(win_str)
>     @times = ([nil]*7).map{[]}

This is the same as Array.new(7){[]}, which is a more usual way to 
express this.

>     win_str << " " #In case of empty
>     win_str.split(/;/).each do |win|
>       days_str = win.match(/(((#{$days.keys.join('|')}|)(
>       |-)?)*)/)[0].strip days = []
>       days_str.scan(/#{$days.keys.join('|')}/) do |day|
>         days << $days[day]
>       end
>       days_str.scan(/(#{$days.keys.join('|')})-(#{$days.keys.join
('|')})/)
>       do
>         a = $days[$1]
>         b = $days[$2]
>         days += (a..(b > a ? b : b+7)).to_a.map{|d|d%7}
>       end
>       days = (0..6).to_a if days.empty?
>       
>       times = []
>       win.scan(/(\d{4})-(\d{4})/) do
>         times << (($1.to_i)...($2.to_i))
>       end
>       times = [0..2400] if times.empty?
>       
>       days.each do |d|
>         times.each do |t|
>           @times[d] << t
>         end
>       end
>     end
>     
>     def include?(time)
>       @times[time.wday].some{|trange| trange ===
>       (time.hour*100+time.min)}
>     end
>   end
> end

Looks generally like my solution.

--Ken

-- 
Ken Bloom. PhD candidate. Linguistic Cognition Laboratory.
Department of Computer Science. Illinois Institute of Technology.
http://www.iit.edu/~kbloom1/