[R] Help needed with aggregate or other solution
Daniel Nordlund
djnordlund at gmail.com
Thu Oct 26 19:03:09 CEST 2017
On 10/26/2017 4:58 AM, Thomas Adams wrote:
> Hi Jeff,
>
> Thank you for the suggestions -- I appreciate your help. Unfortunately, the
> result2 has two problems...
>
> (1) there are now 3 date columns (it looks like 2 cols are merged into 1
> col)
> (2) the output rows should not have any of the basistime dates repeated
> (maybe I misstated the problem); I need the max fcst value by basistime,
> but also list the date value for that row; for example:
>
> basistime fcst
> 1 2012-01-25 15:02:00 47.9
> 2 2012-01-26 15:11:00 50.4
> 3 2012-01-27 01:41:00 46.0
> 4 2012-01-27 10:15:00 47.3
> 5 2012-01-27 15:15:00 47.3
> 6 2012-01-28 14:22:00 46.2
> 7 2012-01-29 13:33:00 45.8
> 8 2012-01-30 14:11:00 44.8
> 9 2012-01-31 14:24:00 43.9
> 10 2012-02-01 14:55:00 41.1
> 11 2012-02-02 14:56:00 38.1
> 12 2012-02-03 14:40:00 36.2
> 13 2012-02-04 15:01:00 34.7
> 14 2012-02-05 15:04:00 33.1
> 15 2012-02-06 14:37:00 32.2
>
> This is very close to what I need. The basistime dates are all unique, with
> the max fcst value for the available basistime dates; but I additionally
> need the corresponding 'date' value.
>
> Best,
> Tom
>
>
>
> On Thu, Oct 26, 2017 at 1:28 AM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us>
> wrote:
>
>> Thanks for the dput...
>>
>> #### reproducible example of split-apply-combine ###
>>
>> dta <- structure(list(date = structure(c(1L, 2L, 3L, 4L, 5L, 6L, 7L,
>>
>> 8L, 9L, 10L, 11L, 12L, 13L, 14L, 15L, 16L, 17L, 18L, 19L, 20L,
>> 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 13L, 14L, 15L, 16L, 17L, 18L,
>> 19L, 20L, 21L, 22L, 23L, 24L, 7L, 8L, 9L, 10L, 11L, 12L, 13L,
>> 14L, 15L, 16L), .Label = c("2012-01-25 18:00:00", "2012-01-26 00:00:00",
>> "2012-01-26 06:00:00", "2012-01-26 12:00:00", "2012-01-26 18:00:00",
>> "2012-01-27 00:00:00", "2012-01-27 06:00:00", "2012-01-27 12:00:00",
>> "2012-01-27 18:00:00", "2012-01-28 00:00:00", "2012-01-28 06:00:00",
>> "2012-01-28 12:00:00", "2012-01-28 18:00:00", "2012-01-29 00:00:00",
>> "2012-01-29 06:00:00", "2012-01-29 12:00:00", "2012-01-29 18:00:00",
>> "2012-01-30 00:00:00", "2012-01-30 06:00:00", "2012-01-30 12:00:00",
>> "2012-01-30 18:00:00", "2012-01-31 00:00:00", "2012-01-31 06:00:00",
>> "2012-01-31 12:00:00", "2012-01-31 13:00:00", "2012-01-31 18:00:00",
>> "2012-02-01 00:00:00", "2012-02-01 06:00:00", "2012-02-01 12:00:00",
>> "2012-02-01 18:00:00", "2012-02-02 00:00:00", "2012-02-02 06:00:00",
>> "2012-02-02 12:00:00", "2012-02-02 18:00:00", "2012-02-03 00:00:00",
>> "2012-02-03 06:00:00", "2012-02-03 12:00:00", "2012-02-03 18:00:00",
>> "2012-02-04 00:00:00", "2012-02-04 06:00:00", "2012-02-04 12:00:00",
>> "2012-02-04 18:00:00", "2012-02-05 00:00:00", "2012-02-05 06:00:00",
>> "2012-02-05 12:00:00", "2012-02-05 18:00:00", "2012-02-06 00:00:00",
>> "2012-02-06 06:00:00", "2012-02-06 12:00:00", "2012-02-06 18:00:00",
>> "2012-02-07 00:00:00", "2012-02-07 06:00:00", "2012-02-07 12:00:00",
>> "2012-02-07 18:00:00", "2012-02-08 00:00:00", "2012-02-08 06:00:00",
>> "2012-02-08 12:00:00", "2012-02-08 18:00:00", "2012-02-09 00:00:00",
>> "2012-02-09 06:00:00", "2012-02-09 12:00:00", "2012-02-09 18:00:00",
>> "2012-02-10 00:00:00", "2012-02-10 06:00:00", "2012-02-10 12:00:00",
>> "2012-02-10 18:00:00", "2012-02-11 00:00:00", "2012-02-11 06:00:00",
>> "2012-02-11 12:00:00", "2012-02-11 18:00:00", "2012-02-12 00:00:00",
>> "2012-02-12 06:00:00", "2012-02-12 12:00:00", "2012-02-12 18:00:00",
>> "2012-02-13 00:00:00", "2012-02-13 06:00:00", "2012-02-13 12:00:00",
>> "2012-02-13 18:00:00", "2012-02-14 00:00:00", "2012-02-14 06:00:00",
>> "2012-02-14 12:00:00", "2012-02-14 18:00:00", "2012-02-15 00:00:00",
>> "2012-02-15 06:00:00", "2012-02-15 12:00:00", "2012-02-15 18:00:00",
>> "2012-02-16 00:00:00", "2012-02-16 06:00:00", "2012-02-16 12:00:00",
>> "2012-02-16 18:00:00", "2012-02-17 00:00:00", "2012-02-17 06:00:00",
>> "2012-02-17 12:00:00", "2012-02-17 18:00:00", "2012-02-18 00:00:00",
>> "2012-02-18 06:00:00", "2012-02-18 12:00:00", "2012-02-18 18:00:00",
>> "2012-02-19 00:00:00", "2012-02-19 06:00:00", "2012-02-19 12:00:00",
>> "2012-02-19 18:00:00", "2012-02-20 00:00:00", "2012-02-20 06:00:00",
>> "2012-02-20 12:00:00", "2012-02-20 18:00:00", "2012-02-21 00:00:00",
>> "2012-02-21 06:00:00", "2012-02-21 12:00:00", "2012-02-21 18:00:00",
>> "2012-02-22 00:00:00", "2012-02-22 06:00:00", "2012-02-22 12:00:00",
>> "2012-02-22 18:00:00", "2012-02-23 00:00:00", "2012-02-23 06:00:00",
>> "2012-02-23 12:00:00", "2012-02-23 18:00:00", "2012-02-24 00:00:00",
>> "2012-02-24 06:00:00", "2012-02-24 12:00:00", "2012-02-24 18:00:00",
>> "2012-02-25 00:00:00", "2012-02-25 06:00:00", "2012-02-25 12:00:00",
>> "2012-02-25 18:00:00", "2012-02-26 00:00:00", "2012-02-26 06:00:00",
>> "2012-02-26 12:00:00", "2012-02-26 18:00:00", "2012-02-27 00:00:00",
>> "2012-02-27 06:00:00", "2012-02-27 12:00:00", "2012-02-27 18:00:00",
>> "2012-02-28 00:00:00", "2012-02-28 06:00:00", "2012-02-28 12:00:00",
>> "2012-02-28 18:00:00", "2012-02-29 00:00:00", "2012-02-29 06:00:00",
>> "2012-02-29 12:00:00", "2012-02-29 18:00:00", "2012-03-01 00:00:00",
>> "2012-03-01 06:00:00", "2012-03-01 12:00:00", "2012-03-01 18:00:00",
>> "2012-03-02 00:00:00", "2012-03-02 06:00:00", "2012-03-02 12:00:00",
>> "2012-03-02 18:00:00", "2012-03-03 00:00:00", "2012-03-03 06:00:00",
>> "2012-03-03 12:00:00", "2012-03-03 18:00:00", "2012-03-04 00:00:00",
>> "2012-03-04 06:00:00", "2012-03-04 12:00:00", "2012-03-04 18:00:00",
>> "2012-03-05 00:00:00", "2012-03-05 06:00:00", "2012-03-05 12:00:00",
>> "2012-03-05 18:00:00", "2012-03-06 00:00:00", "2012-03-06 06:00:00",
>> "2012-03-06 12:00:00", "2012-03-06 18:00:00", "2012-03-07 00:00:00",
>> "2012-03-07 06:00:00", "2012-03-07 12:00:00", "2012-03-07 18:00:00",
>> "2012-03-08 00:00:00", "2012-03-08 06:00:00", "2012-03-08 12:00:00",
>> "2012-03-08 18:00:00", "2012-03-09 00:00:00", "2012-03-09 06:00:00",
>> "2012-03-09 12:00:00", "2012-03-09 18:00:00", "2012-03-10 00:00:00",
>> "2012-03-10 06:00:00", "2012-03-10 12:00:00", "2012-03-10 18:00:00",
>> "2012-03-11 00:00:00", "2012-03-11 06:00:00", "2012-03-11 12:00:00",
>> "2012-03-11 18:00:00", "2012-03-12 00:00:00", "2012-03-12 06:00:00",
>> "2012-03-12 12:00:00", "2012-03-12 18:00:00", "2012-03-13 00:00:00",
>> "2012-03-13 06:00:00", "2012-03-13 12:00:00", "2012-03-13 18:00:00",
>> "2012-03-14 00:00:00", "2012-03-14 06:00:00", "2012-03-14 12:00:00",
>> "2012-03-14 18:00:00", "2012-03-15 00:00:00", "2012-03-15 06:00:00",
>> "2012-03-15 12:00:00", "2012-03-15 18:00:00", "2012-03-16 00:00:00",
>> "2012-03-16 06:00:00", "2012-03-16 12:00:00", "2012-03-16 18:00:00",
>> "2012-03-17 00:00:00", "2012-03-17 06:00:00", "2012-03-17 12:00:00",
>> "2012-03-17 18:00:00", "2012-03-18 00:00:00", "2012-03-18 06:00:00",
>> "2012-03-18 12:00:00", "2012-03-18 18:00:00", "2012-03-19 00:00:00",
>> "2012-03-19 06:00:00", "2012-03-19 12:00:00", "2012-03-19 18:00:00",
>> "2012-03-20 00:00:00", "2012-03-20 06:00:00", "2012-03-20 12:00:00",
>> "2012-03-20 18:00:00", "2012-03-21 00:00:00", "2012-03-21 06:00:00",
>> "2012-03-21 12:00:00", "2012-03-21 18:00:00", "2012-03-22 00:00:00",
>> "2012-03-22 06:00:00", "2012-03-22 12:00:00", "2012-03-22 18:00:00",
>> "2012-03-23 00:00:00", "2012-03-23 06:00:00", "2012-03-23 12:00:00",
>> "2012-03-23 18:00:00", "2012-03-24 00:00:00", "2012-03-24 06:00:00",
>> "2012-03-24 12:00:00", "2012-03-24 18:00:00", "2012-03-25 00:00:00",
>> "2012-03-25 06:00:00", "2012-03-25 12:00:00", "2012-03-25 18:00:00",
>> "2012-03-26 00:00:00", "2012-03-26 06:00:00", "2012-03-26 12:00:00",
>> "2012-03-26 18:00:00", "2012-03-27 00:00:00", "2012-03-27 06:00:00",
>> "2012-03-27 12:00:00", "2012-03-27 18:00:00", "2012-03-28 00:00:00",
>> "2012-03-28 06:00:00", "2012-03-28 12:00:00", "2012-03-28 18:00:00",
>> "2012-03-29 00:00:00", "2012-03-29 06:00:00", "2012-03-29 12:00:00",
>> "2012-03-29 18:00:00", "2012-03-30 00:00:00", "2012-03-30 06:00:00",
>> "2012-03-30 12:00:00", "2012-03-30 18:00:00", "2012-03-31 00:00:00",
>> "2012-03-31 06:00:00", "2012-03-31 12:00:00", "2012-03-31 18:00:00",
>> "2012-04-01 00:00:00", "2012-04-01 06:00:00", "2012-04-01 12:00:00",
>> "2012-04-01 18:00:00", "2012-04-02 00:00:00", "2012-04-02 06:00:00",
>> "2012-04-02 12:00:00", "2012-04-02 18:00:00", "2012-04-03 00:00:00",
>> "2012-04-03 06:00:00", "2012-04-03 12:00:00", "2012-04-03 18:00:00",
>> "2012-04-04 00:00:00", "2012-04-04 06:00:00", "2012-04-04 12:00:00",
>> "2012-04-04 18:00:00", "2012-04-05 00:00:00", "2012-04-05 06:00:00",
>> "2012-04-05 12:00:00", "2012-04-05 18:00:00", "2012-04-06 00:00:00",
>> "2012-04-06 06:00:00", "2012-04-06 12:00:00", "2012-04-06 18:00:00",
>> "2012-04-07 00:00:00", "2012-04-07 06:00:00", "2012-04-07 12:00:00",
>> "2012-04-07 18:00:00", "2012-04-08 00:00:00", "2012-04-08 06:00:00",
>> "2012-04-08 12:00:00", "2012-04-08 18:00:00", "2012-04-09 00:00:00",
>> "2012-04-09 06:00:00", "2012-04-09 12:00:00", "2012-04-09 18:00:00",
>> "2012-04-10 00:00:00", "2012-04-10 06:00:00", "2012-04-10 12:00:00",
>> "2012-04-10 18:00:00", "2012-04-11 00:00:00", "2012-04-11 06:00:00",
>> "2012-04-11 12:00:00", "2012-04-11 18:00:00", "2012-04-12 00:00:00",
>> "2012-04-12 06:00:00", "2012-04-12 12:00:00", "2012-04-12 18:00:00",
>> "2012-04-13 00:00:00", "2012-04-13 06:00:00", "2012-04-13 12:00:00",
>> "2012-04-13 18:00:00", "2012-04-14 00:00:00", "2012-04-14 06:00:00",
>> "2012-04-14 12:00:00", "2012-04-14 18:00:00", "2012-04-15 00:00:00",
>> "2012-04-15 06:00:00", "2012-04-15 12:00:00", "2012-04-15 18:00:00",
>> "2012-04-16 00:00:00", "2012-04-16 06:00:00", "2012-04-16 12:00:00",
>> "2012-04-16 18:00:00", "2012-04-17 00:00:00", "2012-04-17 06:00:00",
>> "2012-04-17 12:00:00", "2012-04-17 18:00:00", "2012-04-18 00:00:00",
>> "2012-04-18 06:00:00", "2012-04-18 12:00:00", "2012-04-18 18:00:00",
>> "2012-04-19 00:00:00", "2012-04-19 06:00:00", "2012-04-19 12:00:00",
>> "2012-04-19 18:00:00", "2012-04-20 00:00:00", "2012-04-20 06:00:00",
>> "2012-04-20 12:00:00", "2012-04-20 18:00:00", "2012-04-21 00:00:00",
>> "2012-04-21 06:00:00", "2012-04-21 12:00:00", "2012-04-21 18:00:00",
>> "2012-04-22 00:00:00", "2012-04-22 06:00:00", "2012-04-22 12:00:00",
>> "2012-04-22 18:00:00", "2012-04-23 00:00:00", "2012-04-23 06:00:00",
>> "2012-04-23 12:00:00", "2012-04-23 18:00:00", "2012-04-24 00:00:00",
>> "2012-04-24 06:00:00", "2012-04-24 12:00:00", "2012-04-24 18:00:00",
>> "2012-04-25 00:00:00", "2012-04-25 06:00:00", "2012-04-25 12:00:00",
>> "2012-04-25 18:00:00", "2012-04-26 00:00:00", "2012-04-26 06:00:00",
>> "2012-04-26 12:00:00", "2012-04-26 18:00:00", "2012-04-27 00:00:00",
>> "2012-04-27 06:00:00", "2012-04-27 12:00:00", "2012-04-27 18:00:00",
>> "2012-04-28 00:00:00", "2012-04-28 06:00:00", "2012-04-28 12:00:00",
>> "2012-04-28 18:00:00", "2012-04-29 00:00:00", "2012-04-29 06:00:00",
>> "2012-04-29 12:00:00", "2012-04-29 18:00:00", "2012-04-30 00:00:00",
>> "2012-04-30 06:00:00", "2012-04-30 12:00:00", "2012-04-30 18:00:00",
>> "2012-05-01 00:00:00", "2012-05-01 06:00:00", "2012-05-01 12:00:00",
>> "2012-05-01 18:00:00", "2012-05-02 00:00:00", "2012-05-02 06:00:00",
>> "2012-05-02 12:00:00", "2012-05-02 18:00:00", "2012-05-03 00:00:00",
>> "2012-05-03 06:00:00", "2012-05-03 12:00:00", "2012-05-03 18:00:00",
>> "2012-05-04 00:00:00", "2012-05-04 06:00:00", "2012-05-04 12:00:00",
>> "2012-05-04 18:00:00", "2012-05-05 00:00:00", "2012-05-05 06:00:00",
>> "2012-05-05 12:00:00", "2012-05-05 18:00:00", "2012-05-06 00:00:00",
>> "2012-05-06 06:00:00", "2012-05-06 12:00:00", "2012-05-06 18:00:00",
>> "2012-05-07 00:00:00", "2012-05-07 06:00:00", "2012-05-07 12:00:00",
>> "2012-05-07 18:00:00", "2012-05-08 00:00:00", "2012-05-08 06:00:00",
>> "2012-05-08 12:00:00", "2012-05-08 18:00:00", "2012-05-09 00:00:00",
>> "2012-05-09 06:00:00", "2012-05-09 12:00:00", "2012-05-09 18:00:00",
>> "2012-05-10 00:00:00", "2012-05-10 06:00:00", "2012-05-10 12:00:00",
>> "2012-05-10 18:00:00", "2012-05-11 00:00:00", "2012-05-11 06:00:00",
>> "2012-05-11 12:00:00", "2012-05-11 18:00:00", "2012-05-12 00:00:00",
>> "2012-05-12 06:00:00", "2012-05-12 12:00:00", "2012-05-12 18:00:00",
>> "2012-05-13 00:00:00", "2012-05-13 06:00:00", "2012-05-13 12:00:00",
>> "2012-05-13 18:00:00", "2012-05-14 00:00:00", "2012-05-14 06:00:00",
>> "2012-05-14 12:00:00", "2012-05-14 18:00:00", "2012-05-15 00:00:00",
>> "2012-05-15 06:00:00", "2012-05-15 12:00:00", "2012-05-15 18:00:00",
>> "2012-05-16 00:00:00", "2012-05-16 06:00:00", "2012-05-16 12:00:00",
>> "2012-05-16 18:00:00", "2012-05-17 00:00:00", "2012-05-17 06:00:00",
>> "2012-05-17 12:00:00", "2012-05-17 18:00:00", "2012-05-18 00:00:00",
>> "2012-05-18 06:00:00", "2012-05-18 12:00:00", "2012-05-18 18:00:00",
>> "2012-05-19 00:00:00", "2012-05-19 06:00:00", "2012-05-19 12:00:00",
>> "2012-05-19 18:00:00", "2012-05-20 00:00:00", "2012-05-20 06:00:00",
>> "2012-05-20 12:00:00", "2012-05-20 18:00:00", "2012-05-21 00:00:00",
>> "2012-05-21 06:00:00", "2012-05-21 12:00:00", "2012-05-21 18:00:00",
>> "2012-05-22 00:00:00", "2012-05-22 06:00:00", "2012-05-22 12:00:00",
>> "2012-05-22 18:00:00", "2012-05-23 00:00:00", "2012-05-23 06:00:00",
>> "2012-05-23 12:00:00", "2012-05-23 18:00:00", "2012-05-24 00:00:00",
>> "2012-05-24 06:00:00", "2012-05-24 12:00:00", "2012-05-24 18:00:00",
>> "2012-05-25 00:00:00", "2012-05-25 06:00:00", "2012-05-25 12:00:00",
>> "2012-05-25 18:00:00", "2012-05-26 00:00:00", "2012-05-26 06:00:00",
>> "2012-05-26 12:00:00", "2012-05-26 18:00:00", "2012-05-27 00:00:00",
>> "2012-05-27 06:00:00", "2012-05-27 12:00:00", "2012-05-27 18:00:00",
>> "2012-05-28 00:00:00", "2012-05-28 06:00:00", "2012-05-28 12:00:00",
>> "2012-05-28 18:00:00", "2012-05-29 00:00:00", "2012-05-29 06:00:00",
>> "2012-05-29 12:00:00"), class = "factor"), basistime = structure(c(1L,
>> 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
>> 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
>> 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
>> 3L), .Label = c("2012-01-25 15:02:00", "2012-01-26 15:11:00",
>> "2012-01-27 01:41:00", "2012-01-27 10:15:00", "2012-01-27 15:15:00",
>> "2012-01-28 14:22:00", "2012-01-29 13:33:00", "2012-01-30 14:11:00",
>> "2012-01-31 14:24:00", "2012-02-01 14:55:00", "2012-02-02 14:56:00",
>> "2012-02-03 14:40:00", "2012-02-04 15:01:00", "2012-02-05 15:04:00",
>> "2012-02-06 14:37:00", "2012-02-07 14:42:00", "2012-02-08 14:44:00",
>> "2012-02-09 14:27:00", "2012-02-10 14:33:00", "2012-02-11 15:05:00",
>> "2012-02-12 15:09:00", "2012-02-13 15:00:00", "2012-02-14 15:10:00",
>> "2012-02-15 14:46:00", "2012-02-16 14:42:00", "2012-02-17 14:14:00",
>> "2012-02-18 15:27:00", "2012-02-19 13:13:00", "2012-02-20 13:56:00",
>> "2012-02-21 14:39:00", "2012-02-22 15:33:00", "2012-02-23 15:14:00",
>> "2012-02-24 15:14:00", "2012-02-25 14:25:00", "2012-02-26 14:08:00",
>> "2012-02-27 14:55:00", "2012-02-28 14:40:00", "2012-02-29 14:45:00",
>> "2012-03-01 15:18:00", "2012-03-02 15:18:00", "2012-03-03 15:43:00",
>> "2012-03-04 15:16:00", "2012-03-05 15:17:00", "2012-03-06 15:03:00",
>> "2012-03-07 14:44:00", "2012-03-08 14:53:00", "2012-03-09 15:10:00",
>> "2012-03-10 14:43:00", "2012-03-11 13:37:00", "2012-03-12 14:58:00",
>> "2012-03-13 14:36:00", "2012-03-14 13:49:00", "2012-03-15 14:32:00",
>> "2012-03-16 15:01:00", "2012-03-17 13:55:00", "2012-03-18 13:44:00",
>> "2012-03-19 13:55:00", "2012-03-20 13:53:00", "2012-03-21 14:07:00",
>> "2012-03-22 14:03:00", "2012-03-23 14:30:00", "2012-03-24 14:47:00",
>> "2012-03-25 14:32:00", "2012-03-26 14:41:00", "2012-03-27 13:51:00",
>> "2012-03-28 13:32:00", "2012-03-29 13:59:00", "2012-03-30 14:15:00",
>> "2012-03-31 14:12:00", "2012-04-01 14:30:00", "2012-04-02 13:43:00",
>> "2012-04-03 13:54:00", "2012-04-04 13:45:00", "2012-04-05 13:46:00",
>> "2012-04-06 13:41:00", "2012-04-07 13:13:00", "2012-04-08 12:59:00",
>> "2012-04-09 13:53:00", "2012-04-10 14:15:00", "2012-04-11 14:26:00",
>> "2012-04-12 14:05:00", "2012-04-13 13:37:00", "2012-04-14 13:52:00",
>> "2012-04-15 15:00:00", "2012-04-16 14:42:00", "2012-04-17 14:21:00",
>> "2012-04-18 14:40:00", "2012-04-19 14:35:00", "2012-04-20 15:14:00",
>> "2012-04-21 14:46:00", "2012-04-22 14:44:00", "2012-04-23 14:33:00",
>> "2012-04-24 14:41:00", "2012-04-25 14:13:00", "2012-04-26 14:19:00",
>> "2012-04-27 14:35:00", "2012-04-28 13:48:00", "2012-04-29 14:12:00",
>> "2012-04-30 13:53:00", "2012-05-02 14:41:00", "2012-05-03 15:01:00",
>> "2012-05-04 15:21:00", "2012-05-05 14:57:00", "2012-05-06 14:09:00",
>> "2012-05-07 14:30:00", "2012-05-08 14:05:00", "2012-05-08 21:21:00",
>> "2012-05-09 15:02:00", "2012-05-10 14:27:00", "2012-05-11 14:47:00",
>> "2012-05-12 13:24:00", "2012-05-13 14:40:00", "2012-05-13 19:24:00",
>> "2012-05-14 14:33:00", "2012-05-15 14:39:00", "2012-05-16 14:07:00",
>> "2012-05-17 13:42:00", "2012-05-18 14:30:00", "2012-05-19 13:59:00",
>> "2012-05-20 14:14:00", "2012-05-21 14:15:00", "2012-05-22 14:18:00",
>> "2012-05-23 14:14:00", "2012-05-24 13:52:00"), class = "factor"),
>> fcst = c(38.7, 38.9, 39.2, 39.8, 40.5, 41.5, 42.5, 43.1,
>> 43.9, 44.5, 44.8, 45, 45, 45.1, 45.4, 45.8, 46.4, 47, 47.5,
>> 47.9, 39.2, 40, 41.8, 42.2, 42.8, 44.4, 45.7, 46.2, 46.2,
>> 46.2, 46.5, 47, 47.5, 47.9, 48.4, 49, 49.5, 49.9, 50.2, 50.4,
>> 41.3, 42.5, 42.8, 42.8, 42.8, 42.9, 43, 43.3, 43.5, 43.8),
>> usgs = c(38.5, 38.6, 38.6, 38.6, 39.1, 39.8, 41.2, 42.9,
>> 43.4, 43.6, 43.4, 43.1, 43, 43.1, 43.5, 43.8, 44.1, 44.2,
>> 44.4, 44.5, 39.1, 39.8, 41.2, 42.9, 43.4, 43.6, 43.4, 43.1,
>> 43, 43.1, 43.5, 43.8, 44.1, 44.2, 44.4, 44.5, 44.5, 44.5,
>> 44.6, 44.2, 41.2, 42.9, 43.4, 43.6, 43.4, 43.1, 43, 43.1,
>> 43.5, 43.8)), .Names = c("date", "basistime", "fcst", "usgs"
>> ), row.names = c(NA, 50L), class = "data.frame")
>>
>> Sys.setenv( "Etc/GMT+8" ) # or whatever is appropriate
>> #> Error in Sys.setenv("Etc/GMT+8"): all arguments must be named
>>
>> dta2 <- dta
>> # bad idea to work with dates as factors
>> dta2$date <- as.POSIXct( as.character( dta2$date ) )
>> dta2$basistime <- as.POSIXct( as.character( dta2$basistime ) )
>>
>> # base R solution
>>
>> dates <- unique( dta2$date )
>> dta2list <- split( dta2, dta2$date )
>> grplist <- lapply( dta2list
>> , function( DF ) {
>> DF[ which.max( DF$fcst ), ]
>> }
>> )
>> result2 <- do.call( rbind, grplist )
>> result2
>> #> date basistime fcst usgs
>> #> 2012-01-25 18:00:00 2012-01-25 18:00:00 2012-01-25 15:02:00 38.7 38.5
>> #> 2012-01-26 00:00:00 2012-01-26 00:00:00 2012-01-25 15:02:00 38.9 38.6
>> #> 2012-01-26 06:00:00 2012-01-26 06:00:00 2012-01-25 15:02:00 39.2 38.6
>> #> 2012-01-26 12:00:00 2012-01-26 12:00:00 2012-01-25 15:02:00 39.8 38.6
>> #> 2012-01-26 18:00:00 2012-01-26 18:00:00 2012-01-25 15:02:00 40.5 39.1
>> #> 2012-01-27 00:00:00 2012-01-27 00:00:00 2012-01-25 15:02:00 41.5 39.8
>> #> 2012-01-27 06:00:00 2012-01-27 06:00:00 2012-01-25 15:02:00 42.5 41.2
>> #> 2012-01-27 12:00:00 2012-01-27 12:00:00 2012-01-25 15:02:00 43.1 42.9
>> #> 2012-01-27 18:00:00 2012-01-27 18:00:00 2012-01-25 15:02:00 43.9 43.4
>> #> 2012-01-28 00:00:00 2012-01-28 00:00:00 2012-01-25 15:02:00 44.5 43.6
>> #> 2012-01-28 06:00:00 2012-01-28 06:00:00 2012-01-26 15:11:00 45.7 43.4
>> #> 2012-01-28 12:00:00 2012-01-28 12:00:00 2012-01-26 15:11:00 46.2 43.1
>> #> 2012-01-28 18:00:00 2012-01-28 18:00:00 2012-01-26 15:11:00 46.2 43.0
>> #> 2012-01-29 00:00:00 2012-01-29 00:00:00 2012-01-26 15:11:00 46.2 43.1
>> #> 2012-01-29 06:00:00 2012-01-29 06:00:00 2012-01-26 15:11:00 46.5 43.5
>> #> 2012-01-29 12:00:00 2012-01-29 12:00:00 2012-01-26 15:11:00 47.0 43.8
>> #> 2012-01-29 18:00:00 2012-01-29 18:00:00 2012-01-26 15:11:00 47.5 44.1
>> #> 2012-01-30 00:00:00 2012-01-30 00:00:00 2012-01-26 15:11:00 47.9 44.2
>> #> 2012-01-30 06:00:00 2012-01-30 06:00:00 2012-01-26 15:11:00 48.4 44.4
>> #> 2012-01-30 12:00:00 2012-01-30 12:00:00 2012-01-26 15:11:00 49.0 44.5
>> #> 2012-01-30 18:00:00 2012-01-30 18:00:00 2012-01-26 15:11:00 49.5 44.5
>> #> 2012-01-31 00:00:00 2012-01-31 00:00:00 2012-01-26 15:11:00 49.9 44.5
>> #> 2012-01-31 06:00:00 2012-01-31 06:00:00 2012-01-26 15:11:00 50.2 44.6
>> #> 2012-01-31 12:00:00 2012-01-31 12:00:00 2012-01-26 15:11:00 50.4 44.2
>>
>> # alternately, use tidyverse
>>
>> library(dplyr)
>> #>
>> #> Attaching package: 'dplyr'
>> #> The following objects are masked from 'package:stats':
>> #>
>> #> filter, lag
>> #> The following objects are masked from 'package:base':
>> #>
>> #> intersect, setdiff, setequal, union
>> result3 <- ( dta2
>> %>% group_by( date )
>> %>% do({
>> DF <- .
>> DF[ which.max( DF$fcst ), ]
>> })
>> %>% ungroup
>> %>% as.data.frame
>> )
>> result3
>> #> date basistime fcst usgs
>> #> 1 2012-01-25 18:00:00 2012-01-25 15:02:00 38.7 38.5
>> #> 2 2012-01-26 00:00:00 2012-01-25 15:02:00 38.9 38.6
>> #> 3 2012-01-26 06:00:00 2012-01-25 15:02:00 39.2 38.6
>> #> 4 2012-01-26 12:00:00 2012-01-25 15:02:00 39.8 38.6
>> #> 5 2012-01-26 18:00:00 2012-01-25 15:02:00 40.5 39.1
>> #> 6 2012-01-27 00:00:00 2012-01-25 15:02:00 41.5 39.8
>> #> 7 2012-01-27 06:00:00 2012-01-25 15:02:00 42.5 41.2
>> #> 8 2012-01-27 12:00:00 2012-01-25 15:02:00 43.1 42.9
>> #> 9 2012-01-27 18:00:00 2012-01-25 15:02:00 43.9 43.4
>> #> 10 2012-01-28 00:00:00 2012-01-25 15:02:00 44.5 43.6
>> #> 11 2012-01-28 06:00:00 2012-01-26 15:11:00 45.7 43.4
>> #> 12 2012-01-28 12:00:00 2012-01-26 15:11:00 46.2 43.1
>> #> 13 2012-01-28 18:00:00 2012-01-26 15:11:00 46.2 43.0
>> #> 14 2012-01-29 00:00:00 2012-01-26 15:11:00 46.2 43.1
>> #> 15 2012-01-29 06:00:00 2012-01-26 15:11:00 46.5 43.5
>> #> 16 2012-01-29 12:00:00 2012-01-26 15:11:00 47.0 43.8
>> #> 17 2012-01-29 18:00:00 2012-01-26 15:11:00 47.5 44.1
>> #> 18 2012-01-30 00:00:00 2012-01-26 15:11:00 47.9 44.2
>> #> 19 2012-01-30 06:00:00 2012-01-26 15:11:00 48.4 44.4
>> #> 20 2012-01-30 12:00:00 2012-01-26 15:11:00 49.0 44.5
>> #> 21 2012-01-30 18:00:00 2012-01-26 15:11:00 49.5 44.5
>> #> 22 2012-01-31 00:00:00 2012-01-26 15:11:00 49.9 44.5
>> #> 23 2012-01-31 06:00:00 2012-01-26 15:11:00 50.2 44.6
>> #> 24 2012-01-31 12:00:00 2012-01-26 15:11:00 50.4 44.2
>>
>> ####################################################
>>
>>
>>
>> On Thu, 26 Oct 2017, Thomas Adams wrote:
>>
>> Hello all!
>>>
>>> I've been struggling with is for many hours today; I'm close to getting
>>> what I want, but not close enough...
>>>
>>> I have a dataframe consisting of two date-time columns followed by two
>>> numeric columns. what I need is the max value (in the first numeric
>>> column)
>>> based on the 2nd date-time column, which is essentially a factor. But, I
>>> want the result to provide both date-time values corresponding to the max
>>> value.
>>>
>>> My data:
>>>
>>> structure(list(date = structure(c(1L, 2L, 3L, 4L, 5L, 6L, 7L,
>>> 8L, 9L, 10L, 11L, 12L, 13L, 14L, 15L, 16L, 17L, 18L, 19L, 20L,
>>> 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 13L, 14L, 15L, 16L, 17L, 18L,
>>> 19L, 20L, 21L, 22L, 23L, 24L, 7L, 8L, 9L, 10L, 11L, 12L, 13L,
>>> 14L, 15L, 16L), .Label = c("2012-01-25 18:00:00", "2012-01-26 00:00:00",
>>> "2012-01-26 06:00:00", "2012-01-26 12:00:00", "2012-01-26 18:00:00",
>>> "2012-01-27 00:00:00", "2012-01-27 06:00:00", "2012-01-27 12:00:00",
>>> "2012-01-27 18:00:00", "2012-01-28 00:00:00", "2012-01-28 06:00:00",
>>> "2012-01-28 12:00:00", "2012-01-28 18:00:00", "2012-01-29 00:00:00",
>>> "2012-01-29 06:00:00", "2012-01-29 12:00:00", "2012-01-29 18:00:00",
>>> "2012-01-30 00:00:00", "2012-01-30 06:00:00", "2012-01-30 12:00:00",
>>> "2012-01-30 18:00:00", "2012-01-31 00:00:00", "2012-01-31 06:00:00",
>>> "2012-01-31 12:00:00", "2012-01-31 13:00:00", "2012-01-31 18:00:00",
>>> "2012-02-01 00:00:00", "2012-02-01 06:00:00", "2012-02-01 12:00:00",
>>> "2012-02-01 18:00:00", "2012-02-02 00:00:00", "2012-02-02 06:00:00",
>>> "2012-02-02 12:00:00", "2012-02-02 18:00:00", "2012-02-03 00:00:00",
>>> "2012-02-03 06:00:00", "2012-02-03 12:00:00", "2012-02-03 18:00:00",
>>> "2012-02-04 00:00:00", "2012-02-04 06:00:00", "2012-02-04 12:00:00",
>>> "2012-02-04 18:00:00", "2012-02-05 00:00:00", "2012-02-05 06:00:00",
>>> "2012-02-05 12:00:00", "2012-02-05 18:00:00", "2012-02-06 00:00:00",
>>> "2012-02-06 06:00:00", "2012-02-06 12:00:00", "2012-02-06 18:00:00",
>>> "2012-02-07 00:00:00", "2012-02-07 06:00:00", "2012-02-07 12:00:00",
>>> "2012-02-07 18:00:00", "2012-02-08 00:00:00", "2012-02-08 06:00:00",
>>> "2012-02-08 12:00:00", "2012-02-08 18:00:00", "2012-02-09 00:00:00",
>>> "2012-02-09 06:00:00", "2012-02-09 12:00:00", "2012-02-09 18:00:00",
>>> "2012-02-10 00:00:00", "2012-02-10 06:00:00", "2012-02-10 12:00:00",
>>> "2012-02-10 18:00:00", "2012-02-11 00:00:00", "2012-02-11 06:00:00",
>>> "2012-02-11 12:00:00", "2012-02-11 18:00:00", "2012-02-12 00:00:00",
>>> "2012-02-12 06:00:00", "2012-02-12 12:00:00", "2012-02-12 18:00:00",
>>> "2012-02-13 00:00:00", "2012-02-13 06:00:00", "2012-02-13 12:00:00",
>>> "2012-02-13 18:00:00", "2012-02-14 00:00:00", "2012-02-14 06:00:00",
>>> "2012-02-14 12:00:00", "2012-02-14 18:00:00", "2012-02-15 00:00:00",
>>> "2012-02-15 06:00:00", "2012-02-15 12:00:00", "2012-02-15 18:00:00",
>>> "2012-02-16 00:00:00", "2012-02-16 06:00:00", "2012-02-16 12:00:00",
>>> "2012-02-16 18:00:00", "2012-02-17 00:00:00", "2012-02-17 06:00:00",
>>> "2012-02-17 12:00:00", "2012-02-17 18:00:00", "2012-02-18 00:00:00",
>>> "2012-02-18 06:00:00", "2012-02-18 12:00:00", "2012-02-18 18:00:00",
>>> "2012-02-19 00:00:00", "2012-02-19 06:00:00", "2012-02-19 12:00:00",
>>> "2012-02-19 18:00:00", "2012-02-20 00:00:00", "2012-02-20 06:00:00",
>>> "2012-02-20 12:00:00", "2012-02-20 18:00:00", "2012-02-21 00:00:00",
>>> "2012-02-21 06:00:00", "2012-02-21 12:00:00", "2012-02-21 18:00:00",
>>> "2012-02-22 00:00:00", "2012-02-22 06:00:00", "2012-02-22 12:00:00",
>>> "2012-02-22 18:00:00", "2012-02-23 00:00:00", "2012-02-23 06:00:00",
>>> "2012-02-23 12:00:00", "2012-02-23 18:00:00", "2012-02-24 00:00:00",
>>> "2012-02-24 06:00:00", "2012-02-24 12:00:00", "2012-02-24 18:00:00",
>>> "2012-02-25 00:00:00", "2012-02-25 06:00:00", "2012-02-25 12:00:00",
>>> "2012-02-25 18:00:00", "2012-02-26 00:00:00", "2012-02-26 06:00:00",
>>> "2012-02-26 12:00:00", "2012-02-26 18:00:00", "2012-02-27 00:00:00",
>>> "2012-02-27 06:00:00", "2012-02-27 12:00:00", "2012-02-27 18:00:00",
>>> "2012-02-28 00:00:00", "2012-02-28 06:00:00", "2012-02-28 12:00:00",
>>> "2012-02-28 18:00:00", "2012-02-29 00:00:00", "2012-02-29 06:00:00",
>>> "2012-02-29 12:00:00", "2012-02-29 18:00:00", "2012-03-01 00:00:00",
>>> "2012-03-01 06:00:00", "2012-03-01 12:00:00", "2012-03-01 18:00:00",
>>> "2012-03-02 00:00:00", "2012-03-02 06:00:00", "2012-03-02 12:00:00",
>>> "2012-03-02 18:00:00", "2012-03-03 00:00:00", "2012-03-03 06:00:00",
>>> "2012-03-03 12:00:00", "2012-03-03 18:00:00", "2012-03-04 00:00:00",
>>> "2012-03-04 06:00:00", "2012-03-04 12:00:00", "2012-03-04 18:00:00",
>>> "2012-03-05 00:00:00", "2012-03-05 06:00:00", "2012-03-05 12:00:00",
>>> "2012-03-05 18:00:00", "2012-03-06 00:00:00", "2012-03-06 06:00:00",
>>> "2012-03-06 12:00:00", "2012-03-06 18:00:00", "2012-03-07 00:00:00",
>>> "2012-03-07 06:00:00", "2012-03-07 12:00:00", "2012-03-07 18:00:00",
>>> "2012-03-08 00:00:00", "2012-03-08 06:00:00", "2012-03-08 12:00:00",
>>> "2012-03-08 18:00:00", "2012-03-09 00:00:00", "2012-03-09 06:00:00",
>>> "2012-03-09 12:00:00", "2012-03-09 18:00:00", "2012-03-10 00:00:00",
>>> "2012-03-10 06:00:00", "2012-03-10 12:00:00", "2012-03-10 18:00:00",
>>> "2012-03-11 00:00:00", "2012-03-11 06:00:00", "2012-03-11 12:00:00",
>>> "2012-03-11 18:00:00", "2012-03-12 00:00:00", "2012-03-12 06:00:00",
>>> "2012-03-12 12:00:00", "2012-03-12 18:00:00", "2012-03-13 00:00:00",
>>> "2012-03-13 06:00:00", "2012-03-13 12:00:00", "2012-03-13 18:00:00",
>>> "2012-03-14 00:00:00", "2012-03-14 06:00:00", "2012-03-14 12:00:00",
>>> "2012-03-14 18:00:00", "2012-03-15 00:00:00", "2012-03-15 06:00:00",
>>> "2012-03-15 12:00:00", "2012-03-15 18:00:00", "2012-03-16 00:00:00",
>>> "2012-03-16 06:00:00", "2012-03-16 12:00:00", "2012-03-16 18:00:00",
>>> "2012-03-17 00:00:00", "2012-03-17 06:00:00", "2012-03-17 12:00:00",
>>> "2012-03-17 18:00:00", "2012-03-18 00:00:00", "2012-03-18 06:00:00",
>>> "2012-03-18 12:00:00", "2012-03-18 18:00:00", "2012-03-19 00:00:00",
>>> "2012-03-19 06:00:00", "2012-03-19 12:00:00", "2012-03-19 18:00:00",
>>> "2012-03-20 00:00:00", "2012-03-20 06:00:00", "2012-03-20 12:00:00",
>>> "2012-03-20 18:00:00", "2012-03-21 00:00:00", "2012-03-21 06:00:00",
>>> "2012-03-21 12:00:00", "2012-03-21 18:00:00", "2012-03-22 00:00:00",
>>> "2012-03-22 06:00:00", "2012-03-22 12:00:00", "2012-03-22 18:00:00",
>>> "2012-03-23 00:00:00", "2012-03-23 06:00:00", "2012-03-23 12:00:00",
>>> "2012-03-23 18:00:00", "2012-03-24 00:00:00", "2012-03-24 06:00:00",
>>> "2012-03-24 12:00:00", "2012-03-24 18:00:00", "2012-03-25 00:00:00",
>>> "2012-03-25 06:00:00", "2012-03-25 12:00:00", "2012-03-25 18:00:00",
>>> "2012-03-26 00:00:00", "2012-03-26 06:00:00", "2012-03-26 12:00:00",
>>> "2012-03-26 18:00:00", "2012-03-27 00:00:00", "2012-03-27 06:00:00",
>>> "2012-03-27 12:00:00", "2012-03-27 18:00:00", "2012-03-28 00:00:00",
>>> "2012-03-28 06:00:00", "2012-03-28 12:00:00", "2012-03-28 18:00:00",
>>> "2012-03-29 00:00:00", "2012-03-29 06:00:00", "2012-03-29 12:00:00",
>>> "2012-03-29 18:00:00", "2012-03-30 00:00:00", "2012-03-30 06:00:00",
>>> "2012-03-30 12:00:00", "2012-03-30 18:00:00", "2012-03-31 00:00:00",
>>> "2012-03-31 06:00:00", "2012-03-31 12:00:00", "2012-03-31 18:00:00",
>>> "2012-04-01 00:00:00", "2012-04-01 06:00:00", "2012-04-01 12:00:00",
>>> "2012-04-01 18:00:00", "2012-04-02 00:00:00", "2012-04-02 06:00:00",
>>> "2012-04-02 12:00:00", "2012-04-02 18:00:00", "2012-04-03 00:00:00",
>>> "2012-04-03 06:00:00", "2012-04-03 12:00:00", "2012-04-03 18:00:00",
>>> "2012-04-04 00:00:00", "2012-04-04 06:00:00", "2012-04-04 12:00:00",
>>> "2012-04-04 18:00:00", "2012-04-05 00:00:00", "2012-04-05 06:00:00",
>>> "2012-04-05 12:00:00", "2012-04-05 18:00:00", "2012-04-06 00:00:00",
>>> "2012-04-06 06:00:00", "2012-04-06 12:00:00", "2012-04-06 18:00:00",
>>> "2012-04-07 00:00:00", "2012-04-07 06:00:00", "2012-04-07 12:00:00",
>>> "2012-04-07 18:00:00", "2012-04-08 00:00:00", "2012-04-08 06:00:00",
>>> "2012-04-08 12:00:00", "2012-04-08 18:00:00", "2012-04-09 00:00:00",
>>> "2012-04-09 06:00:00", "2012-04-09 12:00:00", "2012-04-09 18:00:00",
>>> "2012-04-10 00:00:00", "2012-04-10 06:00:00", "2012-04-10 12:00:00",
>>> "2012-04-10 18:00:00", "2012-04-11 00:00:00", "2012-04-11 06:00:00",
>>> "2012-04-11 12:00:00", "2012-04-11 18:00:00", "2012-04-12 00:00:00",
>>> "2012-04-12 06:00:00", "2012-04-12 12:00:00", "2012-04-12 18:00:00",
>>> "2012-04-13 00:00:00", "2012-04-13 06:00:00", "2012-04-13 12:00:00",
>>> "2012-04-13 18:00:00", "2012-04-14 00:00:00", "2012-04-14 06:00:00",
>>> "2012-04-14 12:00:00", "2012-04-14 18:00:00", "2012-04-15 00:00:00",
>>> "2012-04-15 06:00:00", "2012-04-15 12:00:00", "2012-04-15 18:00:00",
>>> "2012-04-16 00:00:00", "2012-04-16 06:00:00", "2012-04-16 12:00:00",
>>> "2012-04-16 18:00:00", "2012-04-17 00:00:00", "2012-04-17 06:00:00",
>>> "2012-04-17 12:00:00", "2012-04-17 18:00:00", "2012-04-18 00:00:00",
>>> "2012-04-18 06:00:00", "2012-04-18 12:00:00", "2012-04-18 18:00:00",
>>> "2012-04-19 00:00:00", "2012-04-19 06:00:00", "2012-04-19 12:00:00",
>>> "2012-04-19 18:00:00", "2012-04-20 00:00:00", "2012-04-20 06:00:00",
>>> "2012-04-20 12:00:00", "2012-04-20 18:00:00", "2012-04-21 00:00:00",
>>> "2012-04-21 06:00:00", "2012-04-21 12:00:00", "2012-04-21 18:00:00",
>>> "2012-04-22 00:00:00", "2012-04-22 06:00:00", "2012-04-22 12:00:00",
>>> "2012-04-22 18:00:00", "2012-04-23 00:00:00", "2012-04-23 06:00:00",
>>> "2012-04-23 12:00:00", "2012-04-23 18:00:00", "2012-04-24 00:00:00",
>>> "2012-04-24 06:00:00", "2012-04-24 12:00:00", "2012-04-24 18:00:00",
>>> "2012-04-25 00:00:00", "2012-04-25 06:00:00", "2012-04-25 12:00:00",
>>> "2012-04-25 18:00:00", "2012-04-26 00:00:00", "2012-04-26 06:00:00",
>>> "2012-04-26 12:00:00", "2012-04-26 18:00:00", "2012-04-27 00:00:00",
>>> "2012-04-27 06:00:00", "2012-04-27 12:00:00", "2012-04-27 18:00:00",
>>> "2012-04-28 00:00:00", "2012-04-28 06:00:00", "2012-04-28 12:00:00",
>>> "2012-04-28 18:00:00", "2012-04-29 00:00:00", "2012-04-29 06:00:00",
>>> "2012-04-29 12:00:00", "2012-04-29 18:00:00", "2012-04-30 00:00:00",
>>> "2012-04-30 06:00:00", "2012-04-30 12:00:00", "2012-04-30 18:00:00",
>>> "2012-05-01 00:00:00", "2012-05-01 06:00:00", "2012-05-01 12:00:00",
>>> "2012-05-01 18:00:00", "2012-05-02 00:00:00", "2012-05-02 06:00:00",
>>> "2012-05-02 12:00:00", "2012-05-02 18:00:00", "2012-05-03 00:00:00",
>>> "2012-05-03 06:00:00", "2012-05-03 12:00:00", "2012-05-03 18:00:00",
>>> "2012-05-04 00:00:00", "2012-05-04 06:00:00", "2012-05-04 12:00:00",
>>> "2012-05-04 18:00:00", "2012-05-05 00:00:00", "2012-05-05 06:00:00",
>>> "2012-05-05 12:00:00", "2012-05-05 18:00:00", "2012-05-06 00:00:00",
>>> "2012-05-06 06:00:00", "2012-05-06 12:00:00", "2012-05-06 18:00:00",
>>> "2012-05-07 00:00:00", "2012-05-07 06:00:00", "2012-05-07 12:00:00",
>>> "2012-05-07 18:00:00", "2012-05-08 00:00:00", "2012-05-08 06:00:00",
>>> "2012-05-08 12:00:00", "2012-05-08 18:00:00", "2012-05-09 00:00:00",
>>> "2012-05-09 06:00:00", "2012-05-09 12:00:00", "2012-05-09 18:00:00",
>>> "2012-05-10 00:00:00", "2012-05-10 06:00:00", "2012-05-10 12:00:00",
>>> "2012-05-10 18:00:00", "2012-05-11 00:00:00", "2012-05-11 06:00:00",
>>> "2012-05-11 12:00:00", "2012-05-11 18:00:00", "2012-05-12 00:00:00",
>>> "2012-05-12 06:00:00", "2012-05-12 12:00:00", "2012-05-12 18:00:00",
>>> "2012-05-13 00:00:00", "2012-05-13 06:00:00", "2012-05-13 12:00:00",
>>> "2012-05-13 18:00:00", "2012-05-14 00:00:00", "2012-05-14 06:00:00",
>>> "2012-05-14 12:00:00", "2012-05-14 18:00:00", "2012-05-15 00:00:00",
>>> "2012-05-15 06:00:00", "2012-05-15 12:00:00", "2012-05-15 18:00:00",
>>> "2012-05-16 00:00:00", "2012-05-16 06:00:00", "2012-05-16 12:00:00",
>>> "2012-05-16 18:00:00", "2012-05-17 00:00:00", "2012-05-17 06:00:00",
>>> "2012-05-17 12:00:00", "2012-05-17 18:00:00", "2012-05-18 00:00:00",
>>> "2012-05-18 06:00:00", "2012-05-18 12:00:00", "2012-05-18 18:00:00",
>>> "2012-05-19 00:00:00", "2012-05-19 06:00:00", "2012-05-19 12:00:00",
>>> "2012-05-19 18:00:00", "2012-05-20 00:00:00", "2012-05-20 06:00:00",
>>> "2012-05-20 12:00:00", "2012-05-20 18:00:00", "2012-05-21 00:00:00",
>>> "2012-05-21 06:00:00", "2012-05-21 12:00:00", "2012-05-21 18:00:00",
>>> "2012-05-22 00:00:00", "2012-05-22 06:00:00", "2012-05-22 12:00:00",
>>> "2012-05-22 18:00:00", "2012-05-23 00:00:00", "2012-05-23 06:00:00",
>>> "2012-05-23 12:00:00", "2012-05-23 18:00:00", "2012-05-24 00:00:00",
>>> "2012-05-24 06:00:00", "2012-05-24 12:00:00", "2012-05-24 18:00:00",
>>> "2012-05-25 00:00:00", "2012-05-25 06:00:00", "2012-05-25 12:00:00",
>>> "2012-05-25 18:00:00", "2012-05-26 00:00:00", "2012-05-26 06:00:00",
>>> "2012-05-26 12:00:00", "2012-05-26 18:00:00", "2012-05-27 00:00:00",
>>> "2012-05-27 06:00:00", "2012-05-27 12:00:00", "2012-05-27 18:00:00",
>>> "2012-05-28 00:00:00", "2012-05-28 06:00:00", "2012-05-28 12:00:00",
>>> "2012-05-28 18:00:00", "2012-05-29 00:00:00", "2012-05-29 06:00:00",
>>> "2012-05-29 12:00:00"), class = "factor"), basistime = structure(c(1L,
>>> 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
>>> 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
>>> 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
>>> 3L), .Label = c("2012-01-25 15:02:00", "2012-01-26 15:11:00",
>>> "2012-01-27 01:41:00", "2012-01-27 10:15:00", "2012-01-27 15:15:00",
>>> "2012-01-28 14:22:00", "2012-01-29 13:33:00", "2012-01-30 14:11:00",
>>> "2012-01-31 14:24:00", "2012-02-01 14:55:00", "2012-02-02 14:56:00",
>>> "2012-02-03 14:40:00", "2012-02-04 15:01:00", "2012-02-05 15:04:00",
>>> "2012-02-06 14:37:00", "2012-02-07 14:42:00", "2012-02-08 14:44:00",
>>> "2012-02-09 14:27:00", "2012-02-10 14:33:00", "2012-02-11 15:05:00",
>>> "2012-02-12 15:09:00", "2012-02-13 15:00:00", "2012-02-14 15:10:00",
>>> "2012-02-15 14:46:00", "2012-02-16 14:42:00", "2012-02-17 14:14:00",
>>> "2012-02-18 15:27:00", "2012-02-19 13:13:00", "2012-02-20 13:56:00",
>>> "2012-02-21 14:39:00", "2012-02-22 15:33:00", "2012-02-23 15:14:00",
>>> "2012-02-24 15:14:00", "2012-02-25 14:25:00", "2012-02-26 14:08:00",
>>> "2012-02-27 14:55:00", "2012-02-28 14:40:00", "2012-02-29 14:45:00",
>>> "2012-03-01 15:18:00", "2012-03-02 15:18:00", "2012-03-03 15:43:00",
>>> "2012-03-04 15:16:00", "2012-03-05 15:17:00", "2012-03-06 15:03:00",
>>> "2012-03-07 14:44:00", "2012-03-08 14:53:00", "2012-03-09 15:10:00",
>>> "2012-03-10 14:43:00", "2012-03-11 13:37:00", "2012-03-12 14:58:00",
>>> "2012-03-13 14:36:00", "2012-03-14 13:49:00", "2012-03-15 14:32:00",
>>> "2012-03-16 15:01:00", "2012-03-17 13:55:00", "2012-03-18 13:44:00",
>>> "2012-03-19 13:55:00", "2012-03-20 13:53:00", "2012-03-21 14:07:00",
>>> "2012-03-22 14:03:00", "2012-03-23 14:30:00", "2012-03-24 14:47:00",
>>> "2012-03-25 14:32:00", "2012-03-26 14:41:00", "2012-03-27 13:51:00",
>>> "2012-03-28 13:32:00", "2012-03-29 13:59:00", "2012-03-30 14:15:00",
>>> "2012-03-31 14:12:00", "2012-04-01 14:30:00", "2012-04-02 13:43:00",
>>> "2012-04-03 13:54:00", "2012-04-04 13:45:00", "2012-04-05 13:46:00",
>>> "2012-04-06 13:41:00", "2012-04-07 13:13:00", "2012-04-08 12:59:00",
>>> "2012-04-09 13:53:00", "2012-04-10 14:15:00", "2012-04-11 14:26:00",
>>> "2012-04-12 14:05:00", "2012-04-13 13:37:00", "2012-04-14 13:52:00",
>>> "2012-04-15 15:00:00", "2012-04-16 14:42:00", "2012-04-17 14:21:00",
>>> "2012-04-18 14:40:00", "2012-04-19 14:35:00", "2012-04-20 15:14:00",
>>> "2012-04-21 14:46:00", "2012-04-22 14:44:00", "2012-04-23 14:33:00",
>>> "2012-04-24 14:41:00", "2012-04-25 14:13:00", "2012-04-26 14:19:00",
>>> "2012-04-27 14:35:00", "2012-04-28 13:48:00", "2012-04-29 14:12:00",
>>> "2012-04-30 13:53:00", "2012-05-02 14:41:00", "2012-05-03 15:01:00",
>>> "2012-05-04 15:21:00", "2012-05-05 14:57:00", "2012-05-06 14:09:00",
>>> "2012-05-07 14:30:00", "2012-05-08 14:05:00", "2012-05-08 21:21:00",
>>> "2012-05-09 15:02:00", "2012-05-10 14:27:00", "2012-05-11 14:47:00",
>>> "2012-05-12 13:24:00", "2012-05-13 14:40:00", "2012-05-13 19:24:00",
>>> "2012-05-14 14:33:00", "2012-05-15 14:39:00", "2012-05-16 14:07:00",
>>> "2012-05-17 13:42:00", "2012-05-18 14:30:00", "2012-05-19 13:59:00",
>>> "2012-05-20 14:14:00", "2012-05-21 14:15:00", "2012-05-22 14:18:00",
>>> "2012-05-23 14:14:00", "2012-05-24 13:52:00"), class = "factor"),
>>> fcst = c(38.7, 38.9, 39.2, 39.8, 40.5, 41.5, 42.5, 43.1,
>>> 43.9, 44.5, 44.8, 45, 45, 45.1, 45.4, 45.8, 46.4, 47, 47.5,
>>> 47.9, 39.2, 40, 41.8, 42.2, 42.8, 44.4, 45.7, 46.2, 46.2,
>>> 46.2, 46.5, 47, 47.5, 47.9, 48.4, 49, 49.5, 49.9, 50.2, 50.4,
>>> 41.3, 42.5, 42.8, 42.8, 42.8, 42.9, 43, 43.3, 43.5, 43.8),
>>> usgs = c(38.5, 38.6, 38.6, 38.6, 39.1, 39.8, 41.2, 42.9,
>>> 43.4, 43.6, 43.4, 43.1, 43, 43.1, 43.5, 43.8, 44.1, 44.2,
>>> 44.4, 44.5, 39.1, 39.8, 41.2, 42.9, 43.4, 43.6, 43.4, 43.1,
>>> 43, 43.1, 43.5, 43.8, 44.1, 44.2, 44.4, 44.5, 44.5, 44.5,
>>> 44.6, 44.2, 41.2, 42.9, 43.4, 43.6, 43.4, 43.1, 43, 43.1,
>>> 43.5, 43.8)), .Names = c("date", "basistime", "fcst", "usgs"
>>> ), row.names = c(NA, 50L), class = "data.frame")
>>>
>>> aggregate(fcst ~ basistime,data=legacy, FUN= max)
>>>
>>> A snippet...
>>>
>>> basistime fcst
>>> 1 2012-01-25 15:02:00 47.9
>>> 2 2012-01-26 15:11:00 50.4
>>> 3 2012-01-27 01:41:00 46.0
>>> 4 2012-01-27 10:15:00 47.3
>>> 5 2012-01-27 15:15:00 47.3
>>> 6 2012-01-28 14:22:00 46.2
>>> 7 2012-01-29 13:33:00 45.8
>>> 8 2012-01-30 14:11:00 44.8
>>> 9 2012-01-31 14:24:00 43.9
>>> 10 2012-02-01 14:55:00 41.1
>>> 11 2012-02-02 14:56:00 38.1
>>> 12 2012-02-03 14:40:00 36.2
>>> 13 2012-02-04 15:01:00 34.7
>>> 14 2012-02-05 15:04:00 33.1
>>> 15 2012-02-06 14:37:00 32.2
>>>
>>> This is what I want, except I need the other corresponding date-time
>>> column
>>> as well. I've tried this with the date-times as factors and as POSIXct
>>> values and using many of the combinations suggested in the documentation
>>> and other examples. The closest I can get returns the second date as a
>>> numeric value:
>>>
>>> aggregate(cbind(fcst,date) ~ basistime,data=legacy, FUN= max)
>>>
>>> Produces:
>>>
>>> basistime fcst date
>>> 1 2012-01-25 15:02:00 47.9 1327942800
>>> 2 2012-01-26 15:11:00 50.4 1328029200
>>> 3 2012-01-27 01:41:00 46.0 1328072400
>>> 4 2012-01-27 10:15:00 47.3 1328032800
>>> 5 2012-01-27 15:15:00 47.3 1328115600
>>> 6 2012-01-28 14:22:00 46.2 1328202000
>>> 7 2012-01-29 13:33:00 45.8 1328288400
>>> 8 2012-01-30 14:11:00 44.8 1328374800
>>> 9 2012-01-31 14:24:00 43.9 1328461200
>>> 10 2012-02-01 14:55:00 41.1 1328547600
>>> 11 2012-02-02 14:56:00 38.1 1328634000
>>> 12 2012-02-03 14:40:00 36.2 1328720400
>>> 13 2012-02-04 15:01:00 34.7 1328806800
>>> 14 2012-02-05 15:04:00 33.1 1328893200
>>> 15 2012-02-06 14:37:00 32.2 1328979600
>>> 16 2012-02-07 14:42:00 31.2 1329066000
>>> 17 2012-02-08 14:44:00 30.4 1329152400
>>> 18 2012-02-09 14:27:00 30.0 1329238800
>>>
>>>
>>> Help is greatly appreciated!
>>>
>>> Regards,
>>> Tom
>>>
>>> --
>>>
>>> [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help at 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/posti
>>> ng-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>> ------------------------------------------------------------
>> ---------------
>> Jeff Newmiller The ..... ..... Go Live...
>> DCN:<jdnewmil at dcn.davis.ca.us> Basics: ##.#. ##.#. Live
>> Go...
>> Live: OO#.. Dead: OO#.. Playing
>> Research Engineer (Solar/Batteries O.O#. #.O#. with
>> /Software/Embedded Controllers) .OO#. .OO#. rocks...1k
>> ------------------------------------------------------------
>> ---------------
>>
>
>
>
Thomas,
try this. If your data structure is called dta, then
> maxes <- aggregate(dta$fcst, list(dta$basistime), FUN=max, simplify
= TRUE, drop = TRUE)
> want <- merge(dta, maxes, by.x=c('fcst', 'basistime'),
by.y=c('x','Group.1'))
> want
fcst basistime date usgs
1 43.8 2012-01-27 01:41:00 2012-01-29 12:00:00 43.8
2 47.9 2012-01-25 15:02:00 2012-01-30 12:00:00 44.5
3 50.4 2012-01-26 15:11:00 2012-01-31 12:00:00 44.2
>
You can drop the usgs column and reorder the other columns if you wish.
Hope this is helpful,
Dan
--
Daniel Nordlund
Port Townsend, WA USA
More information about the R-help
mailing list