Check if the Object is a List in R Programming – is.list() Function

is.list() function in R Language is used to return TRUE if the specified data is in the form of list, else returns FALSE.

Syntax: is.list(X)

Parameters:
x: different types of data storage

Example 1:

# R program to illustrate
# is.list function

# Initializing some list
a <- list(1, 2, 3)
b <- list(c("Jan", "Feb", "Mar"))
c <- list(matrix(c(1, 2, 3, 4, 5)))
d <- list(list("green", 12.3))

# Calling is.list() function
is.list(a)
is.list(b)
is.list(c)
is.list(d)

Output:

[1] TRUE
[1] TRUE
[1] TRUE
[1] TRUE

Example 2:

# R program to illustrate
# is.list function

# Initializing a data frame "Biochemical Oxygen
# Data" data sets
x <- BOD

# Each row of the data frame is a list
a <- x[2, ]

# Each column of the data frame is not a list
b <- x[, 1]

# Calling is.list() function
is.list(a)
is.list(b)

Output:

[1] TRUE
[1] FALSE