[R] grouping elements of a data frame

[David Winsemius]

On Jan 15, 2013, at 9:10 AM, Nuri Alpay Temiz wrote:

> Hi everyone,
> 
> I have a question on selecting and grouping elements of a data frame. For example:
> 
> A.df<- [ a c 0.9
>             b  x 0.8
>             b z 0.5
>             c y 0.9
>             c x 0.7
>             c z 0.6]

That is not R code. Matlab?, Python? 

> 
> 
> I want to create a list of a data frame that gives me the unique values of column 1 of A.df so that i can create intersects. That is:
> 
> B[a]<- [ c 0.9]
> 
> B[b]<- [ x 0.8
>             z 0.5]
> 
> B[c]<- [ y 0.9
>             x 0.7
>             z 0.6]
> 
> 
> B[c] n B[b] <- c(x,z)
> 

That's some sort of coded message? We are supposed to know what the "n" operation will do when assigned a vector?


Assuming your really do have a dataframe named B:

intersect(B$c, B$b)

Please code up examples in R in the future.

-- 

David Winsemius
Alameda, CA, USA