Arrays of MATLAB objects.

Sparse matrices.

Duplicate category names when you specify them using the categoryNames input argument of the categorical function.

Growth by assignment. For example, assigning a value beyond the end of an array produces an error.

function c = foo() %#codegen
    c = categorical(1:3,1:3,{'small','medium','large'});
    c(4) = 'medium';
end

Adding a category. For example, specifying a new category by using the = operator produces an error, even when the categorical array is unprotected.

function c = foo() %#codegen
    c = categorical(1:3,1:3,{'small','medium','large'});
    c(1) = 'extra-large';
end

Deleting an element. For example, assigning an empty array to an element produces an error.

function c = foo() %#codegen
    c = categorical(1:3,1:3,{'small','medium','large'});
    c(1) = [];
end

Converting categorical values to text by using the char or string functions. To convert elements of a categorical array to text, use the cellstr function.