CODEWITHSUNDEEP
rfunction
mreq
mreq

Reputation: 6542

Difference between c() and append()

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

Upvotes: 47

Views: 47345

Answers (1)

Arun
Arun

Reputation: 118839

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.

Upvotes: 59

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