On Jun 30, 2011, at 12:30 PM, Marc Schwartz wrote:
> On Jun 30, 2011, at 11:20 AM, Edgar Alminar 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
>
>
> That is not the entire dataset....HBA0020366 is missing, as an example.
>
> I don't use the data.table package, but if you are getting an error
> indicating that CONTTIME is a factor, then something is wrong with either the
> data itself (there are non-numeric entries) or the way in which it was
> entered/imported into R.
>
> Thus, I would first check your data for errors. Use str(YourDataSet) to
> review its structure and if CONTTIME is a factor, check into the data to see
> why.
>
> Lastly, review this R FAQ:
>
> http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-do-I-convert-factors-to-numeric_003f
>
> Just as an alternative, with your data in 'DF':
>
>> DF
> 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
>
>
>> aggregate(CONTTIME ~ DF$SCRNO, data = DF, sum)
> DF$SCRNO CONTTIME
> 1 HBA0020036 9
> 2 HBA0020087 3
> 3 HBA0020209 31
> 4 HBA0020213 11
> 5 HBA0020222 9
> 6 HBA0020292 70
Quick typo correction here. the 'DF$' in DF$SCRNO is superfluous. I did not
clean that up before copying and pasting.
> aggregate(CONTTIME ~ SCRNO, data = DF, sum)
SCRNO CONTTIME
1 HBA0020036 9
2 HBA0020087 3
3 HBA0020209 31
4 HBA0020213 11
5 HBA0020222 9
6 HBA0020292 70
Marc
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