[R] Changing time intervals in data set

[Jim Lemon]

Hi Rich,
>From what you sent, it seems like you want to find where the change in
_measurement interval_ occurred. That looks to me as though it is the
first datetime in each row. In the first row, there is a week gap
between the ten and fifteen minute intervals. This may indicate that
no measurements were taken or perhaps they were lost.

Jim

On Thu, Dec 16, 2021 at 8:13 AM Rich Shepard <rshepard using appl-ecosys.com> wrote:
>
> On Wed, 15 Dec 2021, jim holtman wrote:
>
> > At least show a sample of the data and then what you would like as output.
>
> Jim,
>
> There are 813,694 rows of data. As I wrote,
> >> A 33-year set of river discharge data at one gauge location has recording
> >> intervals of 5, 10, and 30 minutes over the period of record.
>
> Also, 15 minute intervals
>
> >> The data.frame/tibble has columns for year, month, day, hour, minute, and
> >> datetime.
>
> As well as a site_nbr.
>
> What I asked is,
>
> >> Would difftime() allow me to find the dates when the changes occurred?
>
> I'm scrolling through the data file (not the R dataframe). The output I've
> so far generated manually:
>
> 1988-10-01 00:10 - 1991-03-12 23:50  10 min
> 1991-03-19 00:00 - 1994-07-05 23:45  15 min
> 2003-04-03 00:00 - 2004-01-31 10:30  30 min
> 2004-01-31 10:40 - 2004-01-31 15:30   5 min
> 2004-01-31 16:00 - 2008-06-27 11:00  30 min
> 2008-06-27 11:10 - 2008-07-07 15:30   5 min
> 2008-07-07 16:00 - 2009-05-26 13:00  30 min
> 2009-05-26 13:15 - 2009-05-27 06:30   5 min
> 2009-05-27 07:00 - 2009-06-11 08:00  30 min
> 2009-06-11 08:15 - 2009-06-12 08:50   5 min
> 2009-06-12 09:00 - 2010-09-07 08:00  30 min
> 2010-09-07 08:20 - 2010-09-07 18:00   5 min
> 2010-09-07 18:30 - 2010-09-09 07:30  30 min
> 2010-09-09 07:45 - 2010-09-13 11:15   5 min
> 2010-09-13 11:30 - 2010-12-01 07:30  30 min
> 2010-12-01 07:50 - 2010-12-02 15:50   5 min
> 2010-12-02 16:00 - 2010-12-17 10:00  30 min
> 2010-12-17 10:05 - 2010-12-20 08:35   5 min
> 2010-12-20 09:00 - 2011-05-20 09:00  30 min
> 2011-05-20 09:05 - 2011-05-23 06:40   5 min
> 2011-05-23 07:00 - 2011-08-18 17:30  30 min
> 2011-08-18 17:45 - 2011-12-14 06:15  15 min
> 2011-12-14 06:20 - 2011-12-14 17:35   5 min
> 2011-12-14 17:45 - 2012-06-28 06:15  15 min
> 2012-06-28 06:25 - 2012-06-28 14:30   5 min
> 2012-06-28 14:45 - 2012-10-12 06:15  15 min
> 2012-10-12 06:25 - 2012-10-12 15:45   5 min
> 2012-10-12 16:00 - 2014-01-17 07:00  15 min
> 2014-01-17 07:05 - 2014-01-21 07:05   5 min
> 2014-01-21 07:15 - 2015-04-03 07:30  15 min
>
> Rich
>
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