Functions: Generating Random Data

Question 1

sample()

Answer 1

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.

Question 2

probability argument

Answer 2

in sample(), To specify how likely each element in the vector x should be selected, use the prob argument. The length of the prob argument should be as long as the x argument. For example, let’s draw 10 samples (with replacement) from the vector [“a”, “b”], but we’ll make the probability of selecting “a” to be .90, and the probability of selecting “b” to be .10

sample(x = c(“a”, “b”),
prob = c(.9, .1),
size = 10,
replace = TRUE)

Question 3

rnorm()

Answer 3

5 samples from a Normal dist with mean = 0, sd = 1

to generate samples from a normal distribution

rnorm(n = 5, mean = 0, sd = 1)

Question 4

uniform distribution

Answer 4

gives equal probabilities to all values between its minimum and maximum

Question 5

runif()

Answer 5

5 samples from Uniform dist with bounds at 0 and 1

To generate samples from a uniform distribution, use the function runif(), the function has 3 arguments:

runif(n = 5, min = 0, max = 1)