[R] Label rows of table by factor level for groups of factors

[Sarah Goslee]

One possible approach is to use unique() to get the list of distinct
combinations, cbind() an identifying variable to that list, then use
merge() to join it to your existing data frame.

But I'm not seeing how you are getting four unique combinations.
Given your sample data (with the missing comma replaced):
> dim(tabledf)
[1] 8 4
> head(desired)
  x1 x2 x3 res
1  0  1  1   3
2  1  1  1   4
3  0  0  1   3
4  1  0  1   4
5  0  1  1   3
6  1  1  1   4

tabledf has 8 rows, not 4, and I don't see how rows 1 and 3
or rows 2 and 4 of your desired df should get the same
classification.

Regardless, if you can make a data frame like tabledf with
an additional column for your desired res variable, you can
merge() it with your original data frame.

Sarah

On Tue, Mar 6, 2012 at 11:06 AM, O'Hanlon, Simon J
<simon.ohanlon at imperial.ac.uk> wrote:
> Dear useRs,
> I am sure this is a fairly simple problem, but I just cannot get my head around it.
>
>
> I have a dataframe which contains several factor variables. I can use table() to tell me how many different combinations there are of these variables. What I should like to do is to add a column to my original dataframe which labels each row according to the unique combination of factors.
>
>
> E.g. in the simple example below I create a dataframe 'df' with 3 columns, the values of which take 0 or 1. I can then classify each row in the table and I find that I have 4 unique combinations of factors. I would now like to add a fourth column to df which labels each row according to whether it was unique combination 1,2,3 or 4:
>
> x1=c(rep(0:1,6))
> x2=c(rep(c(1,1,0,0)6))
> x3=c(rep(1,6),rep(0,6))
> df=data.frame(x1,x2,x3)
> tabledf=as.data.frame(with(df, table(x1,x2,x3)))
> res=c(3,4,3,4,3,4,1,2,1,2,1,2)
> desired=data.frame(x1,x2,x3,res)
> df
> tabledf
> desired
>
>
> I realise that this is probably quite simple to do, I am just struggling to get my head around it! Help much appreciated in advance.
>
-- 
Sarah Goslee
http://www.functionaldiversity.org