Count Number of List Elements in R (original) (raw)

Last Updated : 17 May, 2025

In this article, we will explore how to count the number of elements in a list in R, including both simple and nested lists.

We'll use two key functions:

length() to count the number of top-level elements in a list.
lengths() to count the number of elements within each top-level list component.

These functions are helpful for navigating and analyzing lists in R, especially when dealing with nested structures.

1. Creating a List

To start, we can create a basic list using vectors, character data, or range sequences. Then we use length() to count the number of top-level elements.

R `

a1 <- list("Geeks", "For", "Geeks") print(length(a1))

2. Empty List

Here, we create an empty list and count its elements, which will be 0.

R `

empty_list <- list() print(length(empty_list))

3. List with Range, Vector, and Character Vector

Here we combine numeric and character vectors into a single list and prints the total number of top level list elements.

R `

vec <- 1:5 my_range <- seq(3, 9, by = 2) my_list <- list(numbers = vec, sequence = my_range, fruits = c("apple", "banana", "orange")) print(my_list) print(length(my_list))

Output

$numbers [1] 1 2 3 4 5

$sequence [1] 3 5 7 9

$fruits [1] "apple" "banana" "orange"

[1] 3

4. Counting Elements in Nested List Using `lengths()`

Now we will use lengths() function to get the number of elements inside each top level element of the list (nested lists).

R `

values <- 10:50 names <- c("sravan", "bobby", "ojaswi", "gnanu") data1 <- list(1, 2, 3, 4, 5) data <- list(a1 = values, a2 = names, a3 = data1) print(lengths(data))

5. Using length() and lengths() simultaneously

We will try to understand the difference between length() and lengths() function by implementing the simultaneously. We can observe that:

length(data) counts the top level elements in the list.
lengths(data) counts the number of elements in each nested list. R `

data1 <- list(1, 2, 3, 4, 5) data2 <- list("a", 'b', 'c') data <- list(a1 = data1, a2 = data2) return(length(data)) print("-----------------------------") return(lengths(data))

**Output: