How to Create Factors in R - Step by Step Examples

How to Create Factors in R ?

Answer

To create factors in R, you can use the factor() function. Factors are used to represent categorical data and can be ordered or unordered.


✐ Examples

1 Creating a Factor from a Character Vector

In this example,

  1. We start by creating a character vector named colors which contains the values 'red', 'green', 'blue', and 'green'. This vector represents categorical data.
  2. Next, we use the factor() function to convert the colors vector into a factor. We assign the result to a variable named colors_factor. The factor() function interprets the unique values in the vector as different levels of the factor.
  3. We then print the colors_factor to the console to see the factor levels and the data it contains. Each unique value in the original vector becomes a level of the factor.
  4. Finally, we use the levels() function to print the levels of the factor. This shows all the unique values that the factor can take.

R Program

colors <- c('red', 'green', 'blue', 'green')
colors_factor <- factor(colors)
print(colors_factor)
print(levels(colors_factor))

Output

[1] red   green blue  green
Levels: blue green red
[1] "blue" "green" "red"

2 Creating an Ordered Factor

In this example,

  1. We start by creating a character vector named sizes which contains the values 'small', 'large', 'medium', and 'small'. This vector represents ordered categorical data.
  2. Next, we use the factor() function to convert the sizes vector into a factor, specifying the levels argument to define the order of levels: c('small', 'medium', 'large'). We assign the result to a variable named sizes_factor. The factor() function with the levels argument ensures that the factor levels have a specific order.
  3. We then print the sizes_factor to the console to see the factor levels and the data it contains. The factor levels are now ordered according to the specified levels argument.
  4. Finally, we use the is.ordered() function to check if the factor is ordered, and print the result. This confirms that the factor has an inherent order.

R Program

sizes <- c('small', 'large', 'medium', 'small')
sizes_factor <- factor(sizes, levels = c('small', 'medium', 'large'), ordered = TRUE)
print(sizes_factor)
print(is.ordered(sizes_factor))

Output

[1] small  large  medium small 
Levels: small < medium < large
[1] TRUE

Summary

In this tutorial, we learned How to Create Factors in R language with well detailed examples.


More R Factors Tutorials

  1. How to Create Factors in R ?
  2. How to find Length of a Factor in R ?
  3. How to Loop over a Factor in R ?
  4. How to Convert Data to Factors in R ?
  5. How to Order Factor Levels in R ?
  6. How to Access Factor Levels in R ?
  7. How to Modify Factor Levels in R ?
  8. How to Reorder Factor Levels in R ?
  9. How to Add Levels to a Factor in R ?
  10. How to Drop Levels from a Factor in R ?
  11. How to Rename Levels of a Factor in R ?
  12. How to Use Factors in Data Frames in R ?
  13. How to Generate Summary Statistics for Factors in R ?
  14. How to Merge Factors in R ?
  15. How to Split Data by Factors in R ?
  16. How to Plot Factors in R ?
  17. How to Convert Factors to Numeric in R ?
  18. How to Convert Factors to Character in R ?
  19. How to Handle Missing Values in Factors in R ?
  20. How to Use Factors in Conditional Statements in R ?
  21. How to Compare Factors in R ?
  22. How to Create Ordered Factors in R ?
  23. How to Check if a Variable is a Factor in R ?
  24. How to Use Factors in Statistical Models in R ?
  25. How to Collapse Factor Levels in R ?
  26. How to Use Factors in Grouping Operations in R ?
  27. How to Use Factors in Aggregation Functions in R ?
  28. How to Deal with Unused Factor Levels in R ?
  29. How to Encode and Decode Factors in R ?
  30. How to Use Factors in Regression Analysis in R ?
  31. How to Convert Factors to Dates in R ?