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Re^3: Check if Date interval contains Hour X

by alexm (Chaplain)
on Jul 23, 2009 at 20:08 UTC ( #782777=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Check if Date interval contains Hour X
in thread Check if Date interval contains Hour X

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!


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Re^4: Check if Date interval contains Hour X
by ikegami (Pope) on Jul 23, 2009 at 20:26 UTC
    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.

        my $hour_span = DateTime::Span->from_datetimes( start => $dt, end => $dt );

        should be

        my $hour_span = DateTime::Span->from_datetimes( start => $dt, before => $dt->clone()->add( hours => 1 ), );

        or the more readable

        my $hour_span = DateTime::Span->new( start => $dt, hours => 1, );

        Update: No, neither fix help. They were suppose to make the following match:

        2010-10-10 01:59:59|2010-10-10 01:59:59|blablalblabla

        You need

        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 ); my $dt_tomorrow = $dt->clone()->add( days => 1 ); my $hour_span = DateTime::Span->new( start => $dt, hours => 1 )->union( DateTime::Span->new( start => $dt_tomorrow, hours => 1 )); return 1 if $dt_span->intersects($hour_span); } return 0; }

        And there you go, the four DateTimes per hour I mentioned earlier.

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