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Re^2: Check if Date interval contains Hour X

by ikegami (Pope)
on Jul 23, 2009 at 19:21 UTC ( #782766=note: print w/replies, xml ) Need Help??


in reply to Re: Check if Date interval contains Hour X
in thread Check if Date interval contains Hour X

I thought you were on to something until I realized the real problem is finding the right date to go with the hour. Using ::Span makes things a lot more complicated since you now need to make 4 DateTime objects for every hour.
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Re^3: Check if Date interval contains Hour X
by alexm (Chaplain) on Jul 23, 2009 at 20:08 UTC

    The very first thing that came to my mind after reading the OP was the method DateTime::Span::contains. However, yours is the right approach since that method only works for sets that are fully inside, as the manual says.

    Thanks!

      contains wouldn't work, but intersects would
      ...| 20 | 21 | 22 | 23 | 00 | 01 | 02 | 03 |... (------------) log (----] hour (--) intersection

        You're right again, I just realized a bit later so I've been playing with intersects:

        sub hour_in_range { my ($dt_s, $dt_e, @hours) = @_; my $dt_span = DateTime::Span->from_datetimes( start => $dt_s, end => $dt_e ); for my $hour (@hours) { my $dt = $dt_s->clone() ->truncate( to => 'day' ) ->add( hours => $hour ); $dt->add( days => 1 ) if $dt < $dt_s; my $hour_span = DateTime::Span->from_datetimes( start => $dt, end => $dt ); return 1 if $dt_span->intersects($hour_span); } return 0; }

        It's not as simple and efficient as your approach, but it shows how to use span intersection.

        OTOH, I misunderstood the OP and was thinking that @hours = (1,11) was an interval (1am to 11am), not a list of hours to match.

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[Eily]: The best example of that is the TGV, they couldn't decide who would get it so it's in the middle of nowhere halfway between the two
[LanX]: Eily: that rings a bell
[erix]: interesting difference, I suppose they use different data/routes (and shorter seems better, no?)
[LanX]: Montabaur station
[erix]: (I used http://afstandmete n.nl/ )
LanX The stations of Limburg Süd and Montabaur, which are approximately 20 km apart, ...
[LanX]: teh route I get from gmaps is 1662 km long and is crossing the Swiss Alps (mounting 2400 m) ... I wouldn't try this in December...

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