[R] Subsetting a list

[Patrick Connolly]

On Wed, 19-Oct-2005 at 05:09PM +0200, Martin Maechler wrote:


|> Lists can have 'dim' attributes and hence be treated as arrays;
|> Note that this is pretty rarely used and not too well supported
|> by some tools, one could say even 'print()' :
|> 
|> > set.seed(0); L0 <- L <- lapply(rpois(12, lambda=3), seq); dim(L) <- 3:4; L
|>      [,1]      [,2]      [,3]      [,4]     
|> [1,] Integer,5 Integer,3 Integer,5 Integer,3
|> [2,] Integer,2 Integer,5 Integer,6 1        
|> [3,] Integer,2 Integer,2 Integer,4 Integer,2

for an occasion such as this, it can be clearer to do:

> transform(L)
             X1            X2               X3      X4
1 1, 2, 3, 4, 5       1, 2, 3    1, 2, 3, 4, 5 1, 2, 3
2          1, 2 1, 2, 3, 4, 5 1, 2, 3, 4, 5, 6       1
3          1, 2          1, 2       1, 2, 3, 4    1, 2


best


-- 
Patrick Connolly
HortResearch
Mt Albert
Auckland
New Zealand 
Ph: +64-9 815 4200 x 7188
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