Subset a list (choose matching values for all components)

Question

I try to read out certain elements from a list in a way, thats equivalent to df[, c(1,4,5)] in a data.frame.

> obj <- list(c(1:5)         


        

Answer 1

You should call lapply with a function which is run on every list entry:

obj <- list(c(1:5), c(1:5))
lapply(obj, function(x) x[c(1, 4, 5)])
#[[1]]
[1] 1 4 5

[[2]]
[1] 1 4 5

Answer 2

EDi has a great answer, but you can do it by passing the [ function to lapply plus additional arguments:

lapply(obj, '[', c(1, 4, 5))

You can access this and the other "weird" functions in R by quoting them:

?"["