Table of Contents
Appending values to a list in R can be done using the c() or append() functions. The c() function combines the elements in a vector or list into a single vector, whereas the append() function adds elements to the end of a list. Examples of how to use both functions to append values to a list are provided.
You can use the following syntax to append a single value to a list in R:
#get length of list called my_list
len <- length(my_list)
#append value of 12 to end of list
my_list[[len+1]] <- 12
And you can use the following syntax to append multiple values to a list in R:
#get length of list called my_list
len <- length(my_list)
#define values to append to list
new <- c(3, 5, 12, 14)
#append values to list
i = 1
while(i <= length(new)) {
my_list[[i+len]] <- new[i]
i <- i + 1
}
The following examples show how to use each of these functions in practice.
Example 1: Append a Single Value to a List
Suppose we have the following list in R:
#create list
my_list <- list(7, 14, c(1, 2, 3))
#view list
my_list
[[1]]
[1] 7
[[2]]
[1] 14
[[3]]
[1] 1 2 3
We can use the following syntax to append the value 12 to the end of the list:
#get length of list
len <- length(my_list)
#append value to end of list
my_list[[len+1]] <- 12
#view list
my_list
[[1]]
[1] 7
[[2]]
[1] 14
[[3]]
[1] 1 2 3
[[4]]
[1] 12
Example 2: Append Multiple Values to a List
Suppose we have the following list in R:
#create list
my_list <- list(7, 14, c(1, 2, 3))
#view list
my_list
[[1]]
[1] 7
[[2]]
[1] 14
[[3]]
[1] 1 2 3
We can use the following syntax to append several values to the end of the list:
#get length of list
len <- length(my_list)
#define values to append to list
new <- c(3, 5, 12, 14)
#append values to list
i = 1
while(i <= length(new)) {
my_list[[i+len]] <- new[i]
i <- i + 1
}
#display updated list
my_list
[[1]]
[1] 7
[[2]]
[1] 14
[[3]]
[1] 1 2 3
[[4]]
[1] 3
[[5]]
[1] 5
[[6]]
[1] 12
[[7]]
[1] 14