Difference between c() and append()

Question

What is the difference between using c() and append()? Is there any?

> c(      rep(0,5), rep(3,2) ) [1] 0 0 0 0 0 3 3  > append( rep(0,5), rep(3,2) ) [1] 0 0 0 0 0 3 3 

Answer 1

The way you've used it doesn't show difference between c and append. append is different in the sense that it allows for values to be inserted into a vector after a certain position.

Example:

x <- c(10,8,20) c(x, 6) # always adds to the end # [1] 10 8 20 6 append(x, 6, after = 2) # [1] 10  8  6 20 

If you type append in R terminal, you'll see that it uses c() to append values.

# append function function (x, values, after = length(x))  {     lengx <- length(x)     if (!after)          c(values, x)     # by default after = length(x) which just calls a c(x, values)     else if (after >= lengx)          c(x, values)     else c(x[1L:after], values, x[(after + 1L):lengx]) } 

You can see (the commented part) that by default (if you don't set after= as in your example), it simply returns c(x, values). c is a more generic function that can concatenate values to vectors or lists.