How to convert factor levels to list in R ?

In this article, we are going to discuss how to convert the factor levels to list data structure in R Programming Language.

We can get the levels of the vector using factor() function

Syntax: factor(vector)

Return type: vector elements with levels.

If we want to get only levels, Then we can use levels() function.

Syntax: levels(factor(data))

Example 1: R program to create a character vector and get the levels and convert to list data structure

# Create a vector with elements
data = c("bobby", "sravan", "sravan",
         "pinkey", "rohith","rohith")

# apply factor to vector to get unique data
data = factor(data)

# get the levels
levels = levels(data)

# convert the levels to list
print(list(levels))

Output:

[[1]]
[1] "bobby"  "pinkey" "rohith" "sravan"

Example 2: R program to create a numeric vector and get the levels and convert to list data structure

# Create a vector with elements
data = c(1, 2, 3, 4, 5,
         6, 3, 4, 2, 4)

# apply factor to vector to get unique data
data = factor(data)

# get the levels
levels = levels(data)

# convert the levels to list
print(list(levels))

Output:

[[1]]
[1] "1" "2" "3" "4" "5" "6"

Example 3: convert levels to list of lists

Get each level into one list you can use as.list function.

Syntax: as.list(levels(data))

Code:

# Create a vector with elements
data = c("bobby", "sravan", "sravan",
        "pinkey", "rohith","rohith")

# apply factor to vector to get unique data
data = factor(data)

# get the levels
levels = levels(data)

# convert the levels to list of lists
print(as.list(levels))

Output:

[[1]]
[1] "bobby"

[[2]]
[1] "pinkey"

[[3]]
[1] "rohith"

[[4]]
[1] "sravan"