[R] question about sum of (column) elements in R

[Berend Hasselman]

On 04-12-2012, at 08:59, T Bal wrote:

> Hi,
> I have the following data:
> 
> 0   12
> 1   10
> 1   4
> 1   6
> 1   7
> 1   13
> 2   21
> 2   23
> 2   20
> 3   18
> 3   17
> 3   16
> 3   27
> 3   33
> 4   11
> 4   8
> 4   19
> 4   16
> 4   9
> 
> 
> In this data file I would like to sum the numbers of second column which
> belong to the same number in the first column.
> So the output would be:
> 
> 0     12
> 1     40
> 2     64
>        3     111
>        etc.

Using Pascal's test object you can also use aggregate

aggregate(test$V2,by=list(test$V1),FUN=sum)

Berend