Re: [R] Help needed with aggregate or other solution

2017-10-27 Thread Anthoni, Peter (IMK) 
Hi Thomas,

Would this work:
res1=aggregate(dta[,"fcst"],by=list(basistime=dta[,"basistime"]),FUN=max)
mm=match(paste(res1[,"basistime"],res1[,"x"]),paste(dta[,"basistime"],dta[,"fcst"]))
dta[mm,]
> dta[mm,]
  date   basistime fcst usgs
20 2012-01-30 12:00:00 2012-01-25 15:02:00 47.9 44.5
40 2012-01-31 12:00:00 2012-01-26 15:11:00 50.4 44.2
50 2012-01-29 12:00:00 2012-01-27 01:41:00 43.8 43.8

cheers
Peter



> On 26. Oct 2017, at 17:07, Jeff Newmiller  wrote:
> 
> On Thu, 26 Oct 2017, 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)
> 
> No, there are two date columns. Result2 includes the grouping value as a row 
> name (pulled from the names of the dta2list items by rbind).
> 
>> (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:
> 
> Then try out my code replacing
> 
> dta2list <- split( dta2, dta2$date )
> 
> with
> 
> dta2list <- split( dta2, dta2$basistime )
> 
> and
> 
> %>% group_by( date )
> 
> with
> 
> %>% group_by( basistime )
> 
> Please study how the code works and ask questions based on gaps in that 
> knowledge rather than how the results are not what you expected. This mailing 
> list is not a do-your-work-for-you coding service. Some help pages you should 
> look at include:
> 
> ?rownames
> ?split
> ?lapply
> ?do.call
> ?rbind
> ?group_by
> ?do
> 
> You might also find [1] helpful in general, and [2] helpful for understanding 
> dplyr.
> 
> [1] H. Wickham, The Split-Apply-Combine Strategy for Data Analysis, Journal 
> of Statistical Software, vol. 40, no. 1, Apr. 2011.
> 
> [2] H. Wickham and G. Grolemund, R for Data Science. OReilly UK Ltd, 2017. 
> URL: https://r4ds.had.co.nz.
> 
>>  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 
>> 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
>>

Re: [R] Help needed with aggregate or other solution

2017-10-26 Thread Daniel Nordlund 

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 
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

Re: [R] Help needed with aggregate or other solution

2017-10-26 Thread Jeff Newmiller 

On Thu, 26 Oct 2017, 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)


No, there are two date columns. Result2 includes the grouping value as a 
row name (pulled from the names of the dta2list items by rbind).



(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:


Then try out my code replacing

dta2list <- split( dta2, dta2$date )

with

dta2list <- split( dta2, dta2$basistime )

and

%>% group_by( date )

with

%>% group_by( basistime )

Please study how the code works and ask questions based on gaps in that 
knowledge rather than how the results are not what you expected. This 
mailing list is not a do-your-work-for-you coding service. Some help pages 
you should look at include:


?rownames
?split
?lapply
?do.call
?rbind
?group_by
?do

You might also find [1] helpful in general, and [2] helpful for 
understanding dplyr.


[1] H. Wickham, The Split-Apply-Combine Strategy for Data Analysis, 
Journal of Statistical Software, vol. 40, no. 1, Apr. 2011.


[2] H. Wickham and G. Grolemund, R for Data Science. OReilly UK Ltd, 2017. 
URL: https://r4ds.had.co.nz.




 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 
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

Re: [R] Help needed with aggregate or other solution

2017-10-26 Thread Thomas Adams 
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 
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

Re: [R] Help needed with aggregate or other solution

2017-10-25 Thread Jeff Newmiller 

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",

[R] Help needed with aggregate or other solution

2017-10-25 Thread Thomas Adams 
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",