[R] Adding columns of Aggregates to existing dataframe

[jim holtman]

This should do it for you:

> x <- read.table(textConnection("ID1   ID2
+ A1    B3
+ A1    B4
+ A1    B3
+ A1    B3
+ A2    B1
+ A2    B1
+ A2    B4
+ A3    B2
+ A3    B2
+ A5    B1
+ A5    B1
+ A5    B6
+ A5    B4
+ A6    B2"), header=TRUE)
> cbind(x, countID1=ave(seq_along(x$ID1), x$ID1, FUN=length),
+     countID2=ave(seq_along(x$ID2), x$ID2, FUN=length))
   ID1 ID2 countID1 countID2
1   A1  B3        4        3
2   A1  B4        4        3
3   A1  B3        4        3
4   A1  B3        4        3
5   A2  B1        3        4
6   A2  B1        3        4
7   A2  B4        3        3
8   A3  B2        2        3
9   A3  B2        2        3
10  A5  B1        4        4
11  A5  B1        4        4
12  A5  B6        4        1
13  A5  B4        4        3
14  A6  B2        1        3



On Fri, Jun 20, 2008 at 9:04 PM, tonyxv <tonyxv at gmail.com> wrote:
>
> Hello,
> I have a dataframe
>
>
> ID1   ID2
> A1    B3
> A1    B4
> A1    B3
> A1    B3
> A2    B1
> A2    B1
> A2    B4
> A3    B2
> A3    B2
> A5    B1
> A5    B1
> A5    B6
> A5    B4
> A6    B2
>
>
>
> I want to add extra columns to the dataframe CountID1 and CountID2 which is
> the actual count of values such as A1 etc
> ie
>
>
>
> ID1   ID2    CountID1    CountID2
> A1    B3     4           3
> A1    B4     4           4
> A1    B3     4           3
> A1    B3     4           3
> A2    B1     3           4
> A2    B1     3           4
> A2    B4     3           3
> A3    B2     2           3
> A3    B2     2           3
> A5    B1     4           4
> A5    B1     4           4
> A5    B6     4           1
> A5    B4     4           4
> A6    B2     1           3
>
>
> I know this can be done by first creating temporary aggregate dataframes
> then merging with the original.
> Is there an easier way if i want to calculate many aggregates without having
> to merge many temp tables.
>
>
> Thanks.
> --
> View this message in context: http://www.nabble.com/Adding-columns-of-Aggregates-to-existing-dataframe-tp18039838p18039838.html
> Sent from the R help mailing list archive at Nabble.com.
>
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>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?