What's the difference between lapply and do.call?

Question

I\'m learning R recently and confused by two function: lapplyand do.call. It seems that they\'re just similar to map function in Lisp.

Answer 1

Although there have been many answers, here is my example for reference. Suppose we have a list of data as :

L=list(c(1,2,3), c(4,5,6))

The function lapply returns a list.

lapply(L, sum) 

The above means something like below.

list( sum( L[[1]]) , sum( L[[2]]))

Now let us do the same thing for do.call

do.call(sum, L) 

It means

sum( L[[1]], L[[2]])

In our example, it returns 21. In short, lapply always returns a list while the return type of do.call really depends on the function executed.