How to sort list by first element

Question

I have a list of vectors looking like:

[[1]]
[1] 2 1.0 3.0

[[2]]
[1] 3 3 3

[[3]]
[1] 1 3.0 1.0

and I want it to be sorted by first elemen

Answer 1

Same as the others but using Map to extract the first element of each vector.

L <- list(c(2,1,3), c(3,3,3), c(1,3,1))
idx <- as.numeric(Map(function(vec){vec[1]},L))
L[order(idx, decreasing=TRUE)]