[R] Stumped with subsetting

[Tony Plate]

Seems to work fine for me if I understand correctly what you're trying to 
do (there are some typos in your message, which may mean I'm not 
understanding):

 > data <- data.frame(x=1:3,y=4:6,z=7:9)
 > data[c("x","y")]
   x y
1 1 4
2 2 5
3 3 6
 > mylist <- c("x","y")
 > data[mylist]
   x y
1 1 4
2 2 5
3 3 6
 > data[,mylist]
   x y
1 1 4
2 2 5
3 3 6
 >

I'd generally use the second form of subsetting above (i.e., data[,mylist], 
because that will work with matrices as well).

hope this helps,

Tony Plate

At Thursday 01:22 PM 7/29/2004, Peter Wilkinson wrote:
>This seems like such a trivial thing to do:
>
>given a data.frame DF and variables w,v, x,y,z I can do
>
>DF["x"] or DF[c("x","y")]
>
>if I create a vector, mylist = c("x",y")
>
>then I do DF[mylist]
>
>I am not getting x and y, I get something else.
>
>
>what is the correct way to subset a data.frame by columns using a vector, 
>as if I were doing DF["x","y"]?
>
>Peter
>
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