How to add two vectors in R?

In this tutorial, we will look at how to add two vectors in the R programming language with the help of some examples.

Vector Addition in R

You can use the + operator to add two vectors in R. Arithmetic operations on vectors are computed element-wise. That is when you add two vectors, the corresponding elements are added together.

If the vectors are of the same length, corresponding elements (elements with the same index) are added together. The following image illustrates this.

If the vectors are of different lengths, the shorter vector will be recycled to match the length of the longer vector. The following image shows how this is done.

Examples

Let’s look at some examples of adding two vectors in R.

Add two numeric vectors of the same length in R

First, let’s add two numeric vectors having the same length using the + operator.

# create two vectors
v1 <- c(1, 2, 3)
v2 <- c(0, 1, 2)
# add vectors
v <- v1 + v2
# display the resulting vector
print(v)

Output:

[1] 1 3 5

Here, we add two vectors of length three. The resulting vector is also of length three with each element resulting from the sum of corresponding elements in the two vectors, v1 and v2.

Add two numeric vectors with different lengths in R

Let’s now add two numeric vectors having different lengths.

# create two vectors
v1 <- c(1, 2, 3)
v2 <- c(1, 1, 1, 1, 1)
# add vectors
v <- v1 + v2
# display the resulting vector
print(v)

Output:

Warning message in v1 + v2:
“longer object length is not a multiple of shorter object length”
[1] 2 3 4 2 3

Here, we add vector v1 (of length 3) with vector v2 (of length 5) together. You can see that the resulting vector is of length 5.

The shorter vector is recycled in order to compute the sum with the longer vector. The values 1 and 2 are recycled to the index four and five respectively. Note that we get a warning that the longer vector’s length is not a multiple of the shorter vector’s length. This is why the shorter vector was not completely recycled, only the first two values were recycled to match the length of the longer vector.

Let’s look at another example. Here, the longer vector’s length is a multiple of the shorter vector’s length.

# create two vectors
v1 <- c(1, 2, 3)
v2 <- c(1, 1, 1, 1, 1, 1)
# add vectors
v <- v1 + v2
# display the resulting vector
print(v)

Output:

[1] 2 3 4 2 3 4

We get the resulting vector of length six (same as the length of the longer vector). Also, note that we don’t get any warnings here because the shorter vector is recycled once completely to compute the sum with the longer vector.

You might also be interested in –

• R – Sum of values in a Vector
• Average of Values in an R Vector
• Get the Maximum value in an R Vector