[R] cumulative time durations of specified periods (chron)

From: Sebastian Luque <spluque_at_gmail.com>
Date: Mon 12 Jun 2006 - 13:54:48 EST


Hi,

Say we have two chron vectors representing start and end date/times of an event, respectively:

R> (xfrom <- chron(seq(1.25, 11, 3.25)))
[1] (01/02/70 06:00:00) (01/05/70 12:00:00) (01/08/70 18:00:00)
[4] (01/12/70 00:00:00)

R> (xto <- chron(as.numeric(xfrom) + seq(1.5, 2.25, 0.25)))
[1] (01/03/70 18:00:00) (01/07/70 06:00:00) (01/10/70 18:00:00)
[4] (01/14/70 06:00:00)

and we would like to know how much time is included in a number of intervals within each event. We can define the intervals with two chron vectors:

R> (xt0 <- times(c(0.50, 0)))
[1] 12:00:00 00:00:00

R> (xt1 <- times(c(1 - (1 / 86400), 0.25)))
[1] 23:59:59 06:00:00

So for the first event, 01/02/70 06:00:00 to 01/03/70 18:00:00, the interest is to find how much time corresponds to periods 12:00:00 - 23:59:59 and 00:00:00 - 06:00:00.

I began writing a function to accomplish this task, but am at an impasse. The archives may have something on this, but I haven't found a good search query for it, so I'd appreciate some pointers. Thanks in advance.

Cheers,

-- 
Seb

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Received on Mon Jun 12 13:56:16 2006

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