Functions: Creating Vectors

Question 1

c()

Answer 1

takes several scalars as arguments, and returns a vector containing those objects.

When using c(), place a comma in between the objects (scalars or vectors) you want to combine

a <- c(1, 2, 3, 4, 5)

Print the result
a
##[1] 1 2 3 4 5

Question 2

a:b

Answer 2

The a:b function takes two numeric scalars a and b as arguments, and returns a vector of numbers from the starting point a to the ending point b in steps of 1.

Question 3

seq()

Answer 3

The seq() function is a more flexible version of a:b. Like a:b, seq() allows you to create a sequence from a starting number to an ending number.

However, seq() has additional arguments that allow you to specify either the size of the steps between numbers, or the total length of the sequence.

Question 4

length.out function

Answer 4

an optional argument of the seq() function that tells the sequence how long it can be/how many scalars it will return

Question 5

rep()

Answer 5

The rep() function allows you to repeat a scalar (or vector) a specified number of times, or to a desired length.

rep(x = 3, times = 10)
##[1] 3 3 3 3 3 3 3 3 3 3

rep(x = c(1, 2), each = 3)
##[1] 1 1 1 2 2 2

rep(x = 1:3, length.out = 10)
##[1] 1 2 3 1 2 3 1 2 3 1

Question 6

sample()

Answer 6

From the integers 1:10, draw 5 numbers

function allows you to draw random samples of elements (scalars) from a vector.

sample(x = 1:10, size = 5)
##[1] 6 3 7 10 4

sample(x = 1:5, size = 10, replace = TRUE)
##[1] 4 1 4 3 5 2 1 2 4 4

If you don’t specify the replace argument, R will assume that you are sampling without replacement. In other words, each element can only be sampled once.