Re: [Boost-users] [icl] How to find whether a single day intersects a set of intervals?

Subject: Re: [Boost-users] [icl] How to find whether a single day intersects a set of intervals?
From: Joachim Faulhaber (afojgo_at_[hidden])
Date: 2012-08-21 15:16:59

2012/8/20 Steve Lorimer <steve.lorimer_at_[hidden]>:
> Hi folks
>
> I have the following use case: I want to store a series of time intervals in
> an icl::interval_set and then determine whether a single point in time
> intersects one of these intervals.
>
> Here is my first stab at this:
>
>         icl::interval_set<Time> _badMonths; // Time is an internal class
> which defines all comparison operators
>
>         std::vector<int> badMonths; // populated with YYMM integers (eg:
> 1206 for June 2012)
>
>         for (int m : badMonths)
>         {
>             Time openInterval  = Time(2000 + m / 100, m % 100,     1);
> // 1st day of the month
>             Time closeInterval = Time(2000 + m / 100, m % 100 + 1, 1) -
> TimeSpan::Days(1); // last day of the month
>
>             icl::interval<Time>::type month(openInterval, closeInterval);
>
>             _badMonths.insert(month);
>         }
>
>         // it is now my hope that _badMonths will contain a set of intervals
> where each interval is a month

_badMonths now is a set that equals the union of all inserted
intervals. Consecutive months will coalesce to larger intervals. If
you want to preserve the interval borders you might use
icl::separate_interval_set or icl::split_interval_set.

>
> How do I now check whether a single Time instance  intersects  one of the
> intervals in the set?
>
>
>         Time timepoint;
>         if (_badMonths &=  timepoint)
>             std::cout <<  timepoint  << " intersects bad months" <<
> std::endl;

if (_badMonths &=  timepoint) ... //won't compile

but you can use one of the following methods:

if( icl::contains(_badMonths, timepoint) ){...}
if( icl::within(timepoint, _badMonths) ){...}
if( icl::intersects(_badMonths, timepoint) ){...}
if( _badMonths.find(timepoint) != _badMonths.end() ){...}
if( !icl::is_empty(_badMonths & timepoint) ){...}
if( !(_badMonths &=  timepoint).empty() ){...}

For further information don't hesitate to consult the documentation ;-)
E.g.
http://www.boost.org/doc/libs/1_51_0/libs/icl/doc/html/boost_icl/interface/function_synopsis.html
http://www.boost.org/doc/libs/1_51_0/libs/icl/doc/html/boost_icl/function_reference/containedness.html
http://www.boost.org/doc/libs/1_51_0/libs/icl/doc/html/boost_icl/function_reference/intersection.html

HTH,
Joachim

-- 
Interval Container Library [Boost.Icl]
http://www.joachim-faulhaber.de