MATLAB Programming Fundamentals - MathWorks

Work with Protected Categorical Arrays

This example shows how to work with a categorical array with protected categories.

When you create a categorical array with the categorical function, you have the option

of specifying whether or not the categories are protected. Ordinal categorical arrays

always have protected categories, but you also can create a nonordinal categorical array

that is protected using the 'Protected',true name-value pair argument.

When you assign values that are not in the array's list of categories, the array updates

automatically so that its list of categories includes the new values. Similarly, you can

combine (nonordinal) categorical arrays that have different categories. The categories in

the result include the categories from both arrays.

When you assign new values to a protected categorical array, the values must belong to

one of the existing categories. Similarly, you can only combine protected arrays that have

the same categories.

• If you want to combine two nonordinal categorical arrays that have protected
  categories, they must have the same categories, but the order does not matter. The
  resulting categorical array uses the category order from the first array.


• If you want to combine two ordinal categorical array (that always have protected
  categories), they must have the same categories, including their order.

To add new categories to the array, you must use the function addcats.

Create Ordinal Categorical Array

Create a categorical array containing the sizes of 10 objects. Use the names small,

medium, and large for the values 'S', 'M', and 'L'.

A = categorical({'M';'L';'S';'S';'M';'L';'M';'L';'M';'S'},...

{'S','M','L'},{'small','medium','large'},'Ordinal',true)

A = 10x1 categorical array

medium

large

small

small

medium

large

medium

8 Categorical Arrays