[R] Request

[Sundar Dorai-Raj]

Ghosh Mini wrote:
> 
> Dear all,
> 
> I am trying to learn R.
> Is it possible to find the mean of some rows (of some table) and to put it
> in new table.
> 
> For example we have following table
> 
>          date      x      y      z
> 1  05-23-2001      7      1      3
> 2  05-24-2001      8      4      5
> 3  05-24-2001      6      0      0
> 4  05-24-2001     26      2      6
> 5  06-19-2001      0      7      0
> 6  06-19-2001      5      0      2
> 
> 
> and I want to make the table
> 
>          date      x      y      z
> 1  05-23-2001
> 2  05-24-2001      (mean values for each day's)
> 6  06-19-2001
> 
> Is it possible to do this using R???
> 
> If possible pl. help me. Thanking you.
> 


Let `dframe' contain your first table. Then use aggregate:


aggregate(dframe[, c("x", "y", "z")],
           list(date = dframe$date),
           mean)

HTH,

Sundar