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Categories of categorical array



C = categories(A) returns a cell array of character vectors containing the categories of the categorical array, A.


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Create a categorical array, A.

A = categorical({'plane' 'car' 'train' 'car' 'plane'})
A = 1x5 categorical
     plane      car      train      car      plane 

A is a 1-by-5 categorical array.

Display the categories of A.

C = categories(A)
C = 3x1 cell
    {'car'  }

Since you created A by specifying only an input array, the categories appear in alphabetical order.

Create an ordinal categorical array.

A = categorical({'medium' 'large'; 'small' 'xlarge'; 'large' 'medium'},...
    {'small' 'medium' 'large' 'xlarge'},'Ordinal',true)
A = 3x2 categorical
     medium      large  
     small       xlarge 
     large       medium 

A is a 3-by-2 ordinal categorical array.

Display the categories of A.

C = categories(A)
C = 4x1 cell
    {'small' }
    {'large' }

The categories appear in the order in which you specified them. Since A is ordinal, the categories have the mathematical ordering small < medium < large < xlarge.

Input Arguments

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Categorical array, specified as a vector, matrix, or multidimensional array.


  • C includes all categories in A, even if A does not contain any data from a category. To see the unique values in A, use unique(A).

  • The order of the categories listed in C is the same order used by functions, such as summary and histogram. To change the order of the categories, use reordercats.

Extended Capabilities

Version History

Introduced in R2013b