R help - May 2007 - what fun I need to put in this "tapply"

Hi,
I happened to need generate the following
> t1
  V1 V2 count count2
1  1 11     2      3
2  1 12     2      2
3  2 11     1      3
4  3 13     3      1
5  3 11     3      3
6  3 12     3      2

from
  V1 V2
1  1 11
2  1 12
3  2 11
4  3 13
5  3 11
6  3 12

I am wondering what function of funx I need to put into
tapply(t1[,2], t1[,2] funx)

to get that?

If I use length, I probabaly need to do merge by myself. Is there a better way?

thanks.


-- 
Weiwei Shi, Ph.D
Research Scientist
GeneGO, Inc.

"Did you always know?"
"No, I did not. But I believed..."
---Matrix III

Weiwei Shi said the following on 5/14/2007 11:04 AM:
> Hi,
> I happened to need generate the following
>> t1
>   V1 V2 count count2
> 1  1 11     2      3
> 2  1 12     2      2
> 3  2 11     1      3
> 4  3 13     3      1
> 5  3 11     3      3
> 6  3 12     3      2
> 
> from
>   V1 V2
> 1  1 11
> 2  1 12
> 3  2 11
> 4  3 13
> 5  3 11
> 6  3 12
> 
> I am wondering what function of funx I need to put into
> tapply(t1[,2], t1[,2] funx)
> 
> to get that?
> 
> If I use length, I probabaly need to do merge by myself. Is there a better
way?
> 
> thanks.
> 
> 
I think ?ave would be more useful here:

x <- "  V1 V2
1  1 11
2  1 12
3  2 11
4  3 13
5  3 11
6  3 12"

y <- read.table(textConnection(x))
y$count <- ave(y[, 1], y[, 1], FUN = length)
y$count2 <- ave(y[, 2], y[, 2], FUN = length)

HTH,

--sundar