How to Generate a Sample Using the Sample Function in R?

In this article, we will discuss how to generate a sample using the sample function in R.

Sample() function is used to generate the random elements from the given data with or without replacement.

Syntax:

sample(data, size, replace = FALSE, prob = NULL)

where,

• data can be a vector or a dataframe
• size represents the size of the sample
• replace is used to set the values again repeated if it is set to true
• prob: a vector of probability weights for obtaining the elements of the vector being sampled

Example 1: Generate sample data from the vector

Here, we will generate the n sample data from the given vector with 11 elements using the sample function.

# consider the vector
data=c(23,45,21,34,5,6,7,8,86,45,3)

# get 4 random elements
print(sample(data,4))

# get 1 random element
print(sample(data,1))

# get 6 random elements
print(sample(data,6))

Output:

[1] 45  7  5 34
[1] 3
[1]  5 23  8 21  6 45

Example 2: Generate sample data from the vector by replacing

Here we are going to create a vector with 11 elements and generate the sample data with a replacement.

# consider the vector
data=c(23,45,21,34,5,6,7,8,86,45,3)

# get 4 random elements
print(sample(data,4,replace=TRUE))

# get 1 random element
print(sample(data,1,replace=TRUE))

# get 6 random elements
print(sample(data,6,replace=TRUE))

Output:

[1] 45  5  5  3
[1] 86
[1]  5  5  8  7  8 45

Example 3: Sampling with Uneven Probabilities Using sample Function

Here we are going to select the elements with higher probability than others by setting the probability using the prob parameter.

# consider the vector
data=c(23,45,21,34,5)

# get 10 random elements with probability
print(sample(data, size = 10, replace = TRUE, 
             prob = c(0.6,0.1,0.1,0.1,0.1)))

Output:

 [1] 23 23 23 23 23 45 23 23 23 23

Example 4: Random Sampling of Data Frame Rows Using sample Function

Here we are going to sample the dataframe, let us create a dataframe and sample the rows.

# create dataframe with 2 columns
data=data.frame(col1=c(1:10),col2=c(12:21))

# get the sample of 4 in each column
data[sample(1:nrow(data), size = 4), ] 

Output:

Example 5: Random Sampling of List Elements Using sample Function

Here we are going to sample the data in the list  with size 4

# create list with some integers
data=list(1,2,3,4,5,6)

# get the sample of 4
data[sample(1:length(data), size = 4)] 

Output:

[[1]]
[1] 2

[[2]]
[1] 1

[[3]]
[1] 4

[[4]]
[1] 6