Mastering Data Segmentation: A Guide to Using the cut() Function in R


Steven P. Sanderson II, MPH


March 20, 2024


In the realm of data analysis, understanding how to effectively segment your data is paramount. Whether you’re dealing with age groups, income brackets, or any other continuous variable, the ability to categorize your data can provide invaluable insights. In R, the cut() function is a powerful tool for precisely this purpose. In this guide, we’ll explore how to harness the full potential of cut() to slice and dice your data with ease.

Understanding the cut() Function

The cut() function in R allows you to divide a continuous variable into intervals, or “bins”, based on specified breakpoints. This enables you to convert numerical data into categorical data, making it easier to analyze and interpret.


cut(x, breaks, labels = NULL, right = TRUE, ...)
  • x: The numeric vector to be divided into intervals.
  • breaks: Either a numeric vector of two or more unique cut points or a single number giving the number of intervals into which x is to be cut.
  • labels: Labels for the resulting categories. If NULL, simple integer codes are returned.
  • right: Logical indicating if the intervals should be closed on the right (default) or left.
  • ...: Additional arguments to be passed to cut().


Example 1: Basic Usage

Let’s start with a simple example. Suppose we have a vector representing ages:

ages <- c(21, 35, 42, 18, 65, 28, 51, 40, 22, 60)

Now, let’s use the cut() function to divide these ages into three categories: “Young”, “Middle-aged”, and “Elderly”:

age_groups <- cut(
  breaks = c(0, 30, 50, Inf), 
  labels = c("Young", "Middle-aged", "Elderly")

 [1] Young       Middle-aged Middle-aged Young       Elderly     Young      
 [7] Elderly     Middle-aged Young       Elderly    
Levels: Young Middle-aged Elderly

In this code: - breaks = c(0, 30, 50, Inf) specifies the breakpoints for the age groups. - labels = c("Young", "Middle-aged", "Elderly") assigns labels to each category.

Example 2: Customized Breakpoints

Now, let’s say we want more granular age groups. We can specify custom breakpoints:

custom_breaks <- c(0, 20, 30, 40, 50, 60, Inf)
custom_labels <- c("0-20", "21-30", "31-40", "41-50", "51-60", "61+")
custom_age_groups <- cut(ages, 
                         breaks = custom_breaks, 
                         labels = custom_labels

 [1] 21-30 31-40 41-50 0-20  61+   21-30 51-60 31-40 21-30 51-60
Levels: 0-20 21-30 31-40 41-50 51-60 61+

This will create age groups such as “0-20”, “21-30”, and so on, making our analysis more detailed.

Encouragement to Experiment

The cut() function offers immense flexibility, allowing you to tailor your data segmentation to suit your specific needs. I encourage you to experiment with different breakpoints, labels, and datasets to see how cut() can enhance your data analysis workflows.


In this blog post, we’ve delved into the cut() function in R, exploring its syntax and various applications through practical examples. By mastering the cut() function, you’ll gain a powerful tool for segmenting your data and extracting meaningful insights. So go ahead, unleash the potential of cut() in your next data analysis project!