MATLAB Programming Fundamentals - MathWorks

Combine Categorical Arrays Using Multiplication

This example shows how to use the times function to combine categorical arrays,

including ordinal categorical arrays and arrays with undefined elements. When you call

times on two categorical arrays, the output is a categorical array with new categories.

The set of new categories is the set of all the ordered pairs created from the categories of

the input arrays, or the Cartesian product. times forms each element of the output array

as the ordered pair of the corresponding elements of the input arrays. The output array

has the same size as the input arrays.

Combine Two Categorical Arrays

Combine two categorical arrays using times. The input arrays must have the same

number of elements, but can have different numbers of categories.

A = categorical({'blue','red','green'});

B = categorical({'+','-','+'});

C = A.*B

C = 1x3 categorical array

blue + red - green +

Cartesian Product of Categories

Show the categories of C. The categories are all the ordered pairs that can be created

from the categories of A and B, also known as the Cartesian product.

categories(C)

ans = 6x1 cell array

{'blue +' }

{'blue -' }

{'green +'}

{'green -'}

{'red +' }

{'red -' }

As a consequence, A.*B does not equal B.*A.

D = B.*A

Combine Categorical Arrays Using Multiplication