What is lapply()?

The lapply() function in R applies a function to each element of a list (or vector) and returns a list. It is a versatile tool, especially if you want to preserve the structure of your output as a list.

Here’s a quick example:

# Example list
my_list 

$a
(1) 15

$b
(1) 40

$c
(1) 65

Explanation:

• We made a list my_list consisting of three elements: vectors of numbers.
• Using lapply()we have the sum() function to each element in the list.
• The output, resultis a list where each element is the sum of the numbers in the original list.

This is what lapply() It’s all about giving you a list, no matter what.

What is sapply()?

On the other hand, sapply() is a simplified version of lapply(). It attempts to simplify the result to a vector or matrix if possible, making your output more readable in certain situations.

Let’s look at the same example using sapply():

# Applying a function to each element of the list using sapply
result 

Explanation:

• This time we used sapply() instead of lapply().
• The output is now a simple vector, where each element corresponds to the sum of the numbers in the original list.

Notice how sapply() simplify the result to a vector? This is especially useful if you want your output to be more concise and less complex.

Practical example: average calculation

Let’s look at another example to see the differences more clearly:

# Example list of numeric vectors
data 

$a
(1) 6

$b
(1) 15

$c
(1) 30

# Using sapply to calculate the mean of each vector
mean_sapply 

Explanation:

• We have a list data with three numerical vectors.
• lapply(data, mean) returns a list, where each element is the average of the corresponding vector.
• sapply(data, mean) returns a vector, simplifying the output.

This example clearly shows how lapply() And sapply() treat the output differently. If you need the output as a list, choose lapply(). If a vector meets your needs, sapply() is the better option.