categories

List of categories in categorical array

Syntax

``C = categories(A)``
``C = categories(A,OutputType=type)``

Description

example

````C = categories(A)` returns a list of the categories in the categorical array `A`. The output is a cell array of character vectors.The output lists all categories in `A`, including categories that are not present in any element of `A`. To return a list that includes only the categories that are present in elements of `A`, use the `unique` function.```

example

````C = categories(A,OutputType=type)` specifies the output type. You can return the list of categories as a cell array of character vectors, categorical array, or string array. (since R2024a)```

Examples

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Create a categorical array by using the `categorical` function.

`A = categorical(["plane","car","train","car","plane"])`
```A = 1x5 categorical plane car train car plane ```

To return a list of the categories in `A`, use the `categories` function. The order of the categories was determined when you created `A`. If you do not specify an order when you use `categorical`, then `categorical` calls the `unique` function to determine the order of the categories from the input array.

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

Create a categorical array.

`A = categorical(["plane","car","train","car","plane"])`
```A = 1x5 categorical plane car train car plane ```

To return the list of categories as a categorical array, specify the `OutputType` name-value argument.

`C = categories(A,OutputType="categorical")`
```C = 3x1 categorical car plane train ```

Create an ordinal categorical array. Specify the order of the categories as the mathematical ordering `small < medium < large`.

```A = categorical(["medium";"large";"small";"small";"small";"large"], ... ["small","medium","large"], ... Ordinal=true)```
```A = 6x1 categorical medium large small small small large ```

Return a list of the categories in the ordinal categorical array. The categories appear in the order you specified when you created the categorical array.

`C = categories(A)`
```C = 3x1 cell {'small' } {'medium'} {'large' } ```

Input Arguments

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Input array, specified as a categorical array.

Output data type, specified as one of these options:

• `"char"` — Return a cell array of character vectors. If you specify `"char"`, then the output is equivalent to the output of the first syntax.

• `"string"` — Return a string array.

• `"categorical"` — Return a categorical array.

Tips

• The order of the categories listed in `C` is the same order used by functions that you can call on `A`, such as `summary` and `histogram`. To change the order of the categories, use `reordercats`.

Version History

Introduced in R2013b

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