[R] Help needed with aggregate or other solution
Thomas Adams
tea3rd at gmail.com
Thu Oct 26 06:25:53 CEST 2017
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",
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"2012-05-25 18:00:00", "2012-05-26 00:00:00", "2012-05-26 06:00:00",
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"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",
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"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
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