The is.null Function in R (4 Examples)
Basic R Syntax:
is.null(x)
The R function is.null indicates whether a data object is of the data type NULL (i.e. a missing value). The function returns TRUE in case of a NULL object and FALSE in case that the data object is not NULL. The code above illustrates how to use is.null in R.
In the following article, I’ll provide you with 4 examples for the application of the is.null function in R. Let’s dive in…
Example 1: Check if Object is NULL in R
Consider the following example vector in R:
x1 <- c(3, 7, 1, 5, 2, 8) # Create vector in R
By applying the is.null function we can check whether this data object is NULL. As we know, it is not, and therefore the is.null function returns FALSE:
is.null(x1) # Check if vector is NULL # FALSE
Now, consider the following NULL object in R:
x2 <- NULL # Create NULL object in R
In this case, the is.null function returns TRUE, indicating that the object x2 is NULL:
is.null(x2) # Check if object is NULL # TRUE
Example 2: Check if Object is not NULL
The is.null function can be used the other way around in order to check whether a data object is not NULL. You simply have to put an explanation mark in front of is.null (i.e. !is.null):
!is.null(x1) # Check if vector is not NULL # TRUE !is.null(x2) # Check if object is not NULL # FALSE
Do you need more explanations on Examples 1 and 2 of this page? Then check out the following video of my YouTube channel:
Please accept YouTube cookies to play this video. By accepting you will be accessing content from YouTube, a service provided by an external third party.
If you accept this notice, your choice will be saved and the page will refresh.
Example 3: Check if Data Frame is NULL
The same principle can be applied to a data frame. Let’s load some example data to RStudio:
data("mtcars") # Load mtcars data set head(mtcars) # First 6 rows of mtcars data
Table 1: First 6 Rows of the Example Data Set mtcars.
Now, let’s check whether the mtcars data is a NULL object (obviously it’s not):
is.null(mtcars) # Check if data frame is NULL # FALSE
However, if we convert this data matrix to a NULL object, the is.null function returns TRUE:
mtcars2 <- mtcars # Replicate mtcars data frame mtcars2 <- NULL # Convert mtcars2 data to NULL object is.null(mtcars2) # TRUE
Example 4: Check if List is NULL
As you have seen, the is.null function can be applied to a variety of data classes and formats. This also includes list objects in R. Consider the following example list:
mylist <- list() # Empty list object mylist[[1]] <- x1 # Assign x1 example vector to first list entry mylist[[2]] <- mtcars[1:3, 3:5] # Assign mtcars subset to second list entry
As before, we can apply is.null to the whole list:
is.null(mylist) # Check if list is NULL # FALSE
Again, after transforming the list to NULL, the is.null function returns TRUE:
mylist <- NULL # Convert mylist to NULL is.null(mylist) # Check if list is NULL # TRUE
R provides several other is.xxx functions that are very similar to is.null (e.g. is.na, is.nan, or is.finite). All I’ve show you here is applicable to many other R programming scenarios!
Video Explanation: Logical Values in R
The is.null function returns a logical vector. Do you need more practice with logical vectors in R? Then I can recommend the following tutorial video of the DataCamp YouTube channel:
Please accept YouTube cookies to play this video. By accepting you will be accessing content from YouTube, a service provided by an external third party.
If you accept this notice, your choice will be saved and the page will refresh.
Further Reading
Statistics Globe Newsletter