Hi:
Here's a data.table solution. After I read in your data as a data
frame named dd, I used str() to check its contents:
> str(dd)
'data.frame': 19 obs. of 5 variables:
$ RID : int 43 95 230 230 235 235 247 247 321 321 ...
$ SCRNO : Factor w/ 6 levels "HBA0020036","HBA0020087",..: 1 2 3 3
4 4 5 5 6 6 ...
$ VISCODE : Factor w/ 1 level "bl": 1 1 1 1 1 1 1 1 1 1 ...
$ RECNO : int 1 1 2 1 2 1 1 2 13 5 ...
$ CONTTIME: int 9 3 3 28 5 6 5 4 2 13 ...
If you were getting CONTTIME as a factor, I'm guessing you put all of
this into a matrix (cbind?) and then read it into data.table. If so,
you need to spend a little time reading up on the differences between
matrices and data frames. A data table is meant to be a generalization
of a data frame. It's important that you know the classes of your
objects and how to coerce them from one class to another if necessary.
That aside,
> library(data.table)
data.table 1.6
Quick start guide : vignette("datatable-intro")
Homepage : http://datatable.r-forge.r-project.org/
Help : help("data.table") or ?data.table (includes fast start examples)
> dt <- data.table(dd, key = 'SCRNO')
> dt[, list(csum = sum(CONTTIME)), by = SCRNO]
SCRNO csum
[1,] HBA0020036 9
[2,] HBA0020087 3
[3,] HBA0020209 31
[4,] HBA0020213 11
[5,] HBA0020222 9
[6,] HBA0020292 70
Using the list() wrapper is useful, especially if you want to output
multiple variables or if you want to assign a name to the derived
summary variable.
HTH,
Dennis
On Thu, Jun 30, 2011 at 9:20 AM, Edgar Alminar <eaalmi...@ucsd.edu> wrote:
>>> I did this:
>>>
>>> library(data.table)
>>>
>>> dd <- data.table(bl)
>>> dd[,sum(as.integer(CONTTIME)), by = SCRNO]
>>>
>>> (I used as.integer because I got an error message: sum not meaningful for
>>> factors)
>>>
>>> And got this:
>>>
>>> SCRNO V1
>>> [1,] HBA0020036 111
>>> [2,] HBA0020087 71
>>> [3,] HBA0020209 140
>>> [4,] HBA0020213 189
>>> [5,] HBA0020222 174
>>> [6,] HBA0020292 747
>>> [7,] HBA0020310 57
>>> [8,] HBA0020317 291
>>> [9,] HBA0020365 417
>>> [10,] HBA0020366 124
>>>
>>> All the sums are way too big. Is there something making it not add up
>>> correctly?
>>>
>>> Original dataset:
>>>
> RID SCRNO VISCODE RECNO CONTTIME
> 338 43 HBA0020036 bl 1 9
> 1187 95 HBA0020087 bl 1 3
> 3251 230 HBA0020209 bl 2 3
> 3258 230 HBA0020209 bl 1 28
> 3321 235 HBA0020213 bl 2 5
> 3351 235 HBA0020213 bl 1 6
> 3436 247 HBA0020222 bl 1 5
> 3456 247 HBA0020222 bl 2 4
> 4569 321 HBA0020292 bl 13 2
> 4572 321 HBA0020292 bl 5 13
> 4573 321 HBA0020292 bl 1 25
> 4576 321 HBA0020292 bl 7 5
> 4578 321 HBA0020292 bl 8 2
> 4581 321 HBA0020292 bl 4 4
> 4582 321 HBA0020292 bl 9 5
> 4586 321 HBA0020292 bl 12 2
> 4587 321 HBA0020292 bl 6 2
> 4590 321 HBA0020292 bl 10 3
> 4591 321 HBA0020292 bl 11 7
>
> ______________________________________________
> R-help@r-project.org mailing list
> 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
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.
