Harness the Power of paste() and cat() in R: Combining and Displaying Text Like a Pro


Steven P. Sanderson II, MPH


July 21, 2023


As a programmer in R, you’ll often find yourself working with textual data and need to manipulate or display it in various ways. Two essential functions at your disposal for these tasks are paste() and cat(). These functions are powerful tools that allow you to combine and display text easily and efficiently. In this blog post, we’ll explore the syntax, similarities, and differences between these functions and provide you with practical examples to get you started. Let’s dive in!

Understanding `paste()

The paste() function is used to concatenate multiple strings or vectors of strings together into a single string. Its basic syntax is as follows:

paste(..., sep = " ", collapse = NULL)

The ellipsis ... represents the input strings or vectors that you want to combine. The sep argument is optional and specifies the separator to be used between the elements. By default, it is a space. The collapse argument is also optional and specifies the separator to be used between the concatenated strings when the input contains multiple elements (vectors). By default, it is NULL, which means no collapsing will occur.

Examples of paste()

Let’s see some examples of using paste():

Example 1: Basic Concatenation

fruit1 <- "apple"
fruit2 <- "orange"
result <- paste(fruit1, fruit2)
print(result) # Output: "apple orange"
[1] "apple orange"

Example 2: Using Different Separator

months <- c("January", "February", "March")
result <- paste(months, collapse = ", ")
print(result) # Output: "January, February, March"
[1] "January, February, March"

Understanding cat()

The cat() function is used to concatenate and display strings, providing greater flexibility in formatting the output. Its basic syntax is as follows:

cat(..., sep = " ", file = "", append = FALSE)

The ellipsis ... works similarly to paste(), representing the input strings or vectors to be concatenated. The sep argument is also optional and specifies the separator between the concatenated elements. However, unlike paste(), the default separator is a space. The file argument allows you to specify the output file where the concatenated text will be written (if not to the console). The append argument is a logical value, indicating whether to append the output to an existing file (if file is provided).

Examples of cat()

Now, let’s explore some examples of using cat():

Example 1: Basic Concatenation and Display

fruit1 <- "apple"
fruit2 <- "orange"
cat("My favorite fruits are", fruit1, "and", fruit2) # Output: "My favorite fruits are apple and orange"
My favorite fruits are apple and orange

Example 2: Output to File

numbers <- 1:5
file_path <- "numbers.txt"
cat(numbers, file = file_path)
# The content of "numbers.txt": 1 2 3 4 5

Similarities and Differences

  • Both paste() and cat() can concatenate strings or vectors of strings.
  • The sep argument is present in both functions, but they have different default values. For paste(), the default is a space, while for cat(), it is also a space but can be easily customized.
  • paste() returns the concatenated string, which you can store in a variable or use for further processing. On the other hand, cat() immediately prints the concatenated text to the console (or a file if specified), but it doesn’t return anything.
  • With cat(), you can control the formatting and appearance of the output more effectively, especially when dealing with complex displays. No line feeds are output unless explicitly stated and it is useful for producing output in user-defined functions.


Both paste() and cat() are indispensable tools in R for manipulating and displaying text data. Understanding their differences and similarities will help you choose the right function for different scenarios. We encourage you to experiment with these functions on your own. Get creative, combine them with other R functions, and explore the diverse world of text manipulation in R. Happy coding!