%% Remove Categories and Make Corresponding Values Undefined
% Create a categorical array, A, containing modes of transportation.

A = categorical({'plane' 'car'; 'train' 'car'; 'plane' 'car'})

% A is a 3-by-2 categorical array.
%
% Display the categories of A.

categories(A)

% A has three categories, car, plane, and train.
%
% Remove the category, train.

B = removecats(A,'train')

% The element that was from the category train is now undefined.
%
% Display the categories of B.

categories(B)

% B has one fewer category than A.
% Copyright 2012 The MathWorks, Inc.