Sorting list of matrices by the first column

Question

I have a list containing 4 matrices, each with 21 random numbers in 3 columns and 7 rows.

I want to create new list using lapply function in which each matrix is sorted by the first column.

I tried:

#example data
set.seed(1)
list.a <- replicate(4, list(matrix(sample(1:99, 21), nrow=7)))

ordered <- order(list.a[,1])

lapply(list.a, function(x){[ordered,]})

but at the first step the R gives me error "incorrect number of dimensions". Don't know what to do. It works with one matrix, though.

Please help me. Thanks!

Answer 1

You were almost there - but you would need to iterate through the list to reorder each matrix.

Its easier to do this is one lapply statement

lapply(list.a, function(x) x[order(x[,1]),])

Note that x in the function call represents the matrices in the list.