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 <rshep...@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 > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
