You can use the **length() **function in R to calculate the length of vectors, lists, and other objects.

This function uses the following basic syntax:

length(x)

where:

**x**: The name of the object to calculate length for

The following examples show how to use this function in different scenarios.

**Example 1: Use length() with Vector**

The following code shows how to use the **length()** function to calculate the number of elements in a vector:

#create vector my_vector <- c(2, 7, 6, 6, 9, 10, 14, 13, 4, 20, NA) #calculate length of vector length(my_vector) [1] 11

We can see that the vector has 11 total elements.

Note that **length()** also counts NA values.

To exclude NA values when calculating the length of a vector, we can use the following syntax:

#create vector my_vector <- c(2, 7, 6, 6, 9, 10, 14, 13, 4, 20, NA) #calculate length of vector, excluding NA values sum(!is.na(my_vector)) [1] 10

We can see that the vector has 10 elements that are non-NA values.

**Example 2: ****Use length() with List**

The following code shows how to use the **length() **function to calculate the length of an entire list along with the length of a specific element in a list:

#create list my_list <- list(A=1:5, B=c('hey', 'hi'), C=c(3, 5, 7)) #calculate length of entire list length(my_list) [1] 3 #calculate length of first element in list length(my_list[[1]]) [1] 5

From the output we can see that the list has **3** total elements and we can see that the first element in the list has a length of **5**.

**Example 3: ****Use length() with Data Frame**

If we use the **length() **function with a data frame in R, it will return the number of columns in the data frame:

#create data frame df <- data.frame(team=c('A', 'B', 'B', 'B', 'C', 'D'), points=c(10, 15, 29, 24, 30, 31)) #view data frame df team points 1 A 10 2 B 15 3 B 29 4 B 24 5 C 30 6 D 31 #calculate length of data frame (returns number of columns) length(df) [1] 2

If we would like to calculate the number of rows instead, we can use the **nrow()** function:

#calculate number of rows in data frame nrow(df) [1] 6

This tells us that there are **6** total rows in the data frame.

**Example 4: ****Use length() with String**

If we use the **length() **function with a string in R, it will typically just return a value of one:

#define string my_string <- "hey there" #calculate length of string length(my_string) [1] 1

To actually count the number of characters in a string, we can use the **nchar()** function instead:

#define string my_string <- "hey there" #calculate total characters in string nchar(my_string) [1] 9

This tells us that there are **9** total characters in the string, including spaces.

**Additional Resources**

The following tutorials explain how to perform other common operations in R:

How to Count Observations by Group in R

How to Count Number of Rows in R

How to Select Random Rows in R

#calculate length of vector, excluding NA values

sum(!is.na(my_vector))

this should be length and not sum

length(!is.na(my_vector))

Rupali Desai