categories

Categories of categorical array

Syntax

C = categories(A)

Description

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

Examples

List Categories in Categorical Array

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'  }
    {'plane'}
    {'train'}

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

List Categories in Ordinal Categorical Array

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' }
    {'medium'}
    {'large' }
    {'xlarge'}

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

A — Categorical array

vector | matrix | multidimensional array

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

Tips

• 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

Tall Arrays

Calculate with arrays that have more rows than fit in memory.

This function fully supports tall arrays. For more information, see Tall Arrays.

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

This function fully supports code generation. For more information, see Code Generation for Categorical Arrays (MATLAB Coder).

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).