[R] "unique" rows in data frame

[John Kane]

?aggregate

x <- data.frame(a= as.factor(c("A",  "B" , "B" ,"C"
,"B", "A", "D")),
 b = c(3,    2,    1,   1,   2,    3,  7))

aggregate(x[,2], list(x[,1]), mean)


--- Dieter Best <dieterbest_2000 at yahoo.com> wrote:

> Hello there, 
>    
>   I have a data frame a small version of which could
> look like the following:
>    
>     x1 x2
> 1  A  1
> 2  B  2
> 3  B  3
>    
>   Now I need to remove rows which are duplicate in
> x1, i.e. in the example above I would remove row 3. 
>    
>   I have an ugly solution with for and while loops
> and ifs. ... And of course my data set is much
> larger and my solution takes along time. 
>    
>   Any ideas what could be the best way to do this in
> R?
>    
>   Better yet: I actually would like to sort of
> collapse row 2 and 3 in the example above by
> replacing 2 and 3 with a new row 2 which has in x2
> the mean of old x2 of row 2 and 3 (maybe this is
> poorly said).
>    
>   Anyways, thanks a lot in advance for suggestions.
>    
>   -- D
> 
> 
>        
> ---------------------------------
> 
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> 
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