[R] Sum Question

[Rolf Turner]

The simplest way is:

xxx <- with(clyde,tapply(CONTTIME,SCRNO,sum))

You  could also do:

xxx <- by(clyde,clyde[["SCRNO"]],function(x){sum(x[["CONTTIME"]])})

but this gives somewhat messy output; the aforesaid output may be
convenient for some purposes, not for others.

     cheers,

         Rolf Turner

On 30/06/11 09:38, Edgar Alminar wrote:
> Hello,
> I have the following dataset (this is a piece of a much larger set):
>
>       RID      SCRNO VISCODE RECNO CONTTIME
> 23    18 HBA0190012      bl     1        5
> 24    18 HBA0190012      bl     3        5
> 28    18 HBA0190012      bl     5        5
> 29    18 HBA0190012      bl     2        5
> 32    18 HBA0190012      bl     4        5
> 38    19 HBA0190013      bl     2       35
> 50    19 HBA0190013      bl     1        5
> 57    20 HBA0190014      bl     1       10
> 61    21 HBA0200015      bl     2       30
> 64    21 HBA0200015      bl     3       90
> 67    21 HBA0200015      bl     4       90
> 72    21 HBA0200015      bl     8        2
> 76    21 HBA0200015      bl     1       60
> 88    22 HBA0190016      bl     1       25
> 97    23 HBA0190017      bl     3       85
> 99    23 HBA0190017      bl     1        5
> 103   23 HBA0190017      bl     2        5
> 122   25 HBA0190019      bl     1       20
> 145   26 HBA0200020      bl     1       60
> 170   27 HBA0190021      bl     1        3
> 190   28 HBA0220022      bl     1       40
> 194   29 HBA0220023      bl     1       25
> 223   29 HBA0220023      bl     2       25
>
> And I would like to output a list of the sums of CONTTIME for each SCRNO. What is the best way to do that? Any help would be greatly appreciated.
>
> Thanks!
> Edgar
>
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