Do R Function Operate In Place

R Programming

When working with R programming, one of the common questions that often arises is whether R functions operate in place. As a data scientist who frequently uses R for statistical analysis and data visualization, I have encountered this question numerous times. In this article, I will delve into the concept of operating in place in R functions, providing a detailed explanation and exploring some examples.

Understanding Operating in Place

Operating in place refers to the concept of modifying a variable or data structure directly without creating a new copy. In some programming languages, certain functions or operations modify the original data directly, while in others, a new copy of the data is created with the modifications.

R Functions and Operating in Place

In R, the concept of operating in place is not straightforward. Unlike languages such as Python, where some functions explicitly operate in place (e.g., using the inplace=True parameter), R tends to favor immutability by default.

Most R functions do not operate in place, meaning they typically return a new copy of the modified data rather than modifying the original object directly. This is in line with R’s functional programming paradigm, which emphasizes the use of pure functions and immutable data structures.

Example 1: Modifying a Vector

Consider the following example of modifying a vector in R:

# Original vector
original_vector <- c(1, 2, 3, 4, 5) # Using the `append` function modified_vector <- append(original_vector, 6)

In this example, the append function does not operate in place. Instead, it returns a new vector with the additional element, leaving the original original_vector unchanged.

Example 2: Modifying a Data Frame

Let's take a look at modifying a data frame in R:

# Original data frame
original_df <- data.frame(ID = 1:3, Name = c("Alice", "Bob", "Charlie")) # Using the `mutate` function from the dplyr package modified_df <- original_df %>% mutate(Age = c(25, 30, 28))

Similar to the previous example, the mutate function from the dplyr package does not operate in place. It returns a new modified data frame while leaving the original original_df unchanged.

The Exception: Reference Classes

While most R functions do not operate in place, it's important to note that R does have a mechanism for creating mutable objects through reference classes. Reference classes allow for object-oriented programming in R and enable mutable state within objects, which deviates from the default immutability of R objects.


In conclusion, the majority of R functions do not operate in place and instead favor immutability by returning new copies of the modified data. Understanding this behavior is crucial for writing efficient and predictable R code, especially when dealing with large datasets and complex data manipulation tasks. While immutability offers benefits such as avoiding unintended side effects, it's essential to be aware of exceptions such as reference classes when working with mutable objects in R.