# mergelevels

(Not Recommended) Merge levels of nominal or ordinal arrays

The `nominal` and `ordinal` array data types are not recommended. To represent ordered and unordered discrete, nonnumeric data, use the Categorical Arrays data type instead.

## Syntax

``B = mergelevels(A,oldlevels)``
``B = mergelevels(A,oldlevels,newlevel)``

## Description

````B = mergelevels(A,oldlevels)` merges two or more levels of `A`. If `A` is a `nominal` array, `mergelevels` uses the first label in `oldlevels` as the new level.If `A` is an `ordinal` array, the levels specified by `oldlevels` must be consecutive, and `mergelevels` uses the label corresponding to the lowest level in `oldlevels` as the label for the new level. ```

example

````B = mergelevels(A,oldlevels,newlevel)` merges two or more levels into the new level with label `newlevel`.```

## Examples

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Create a nominal array from data in a cell array.

```colors = nominal({'r','b','g';'g','r','b';'b','r','g'},... {'blue','green','red'})```
```colors = 3x3 nominal red blue green green red blue blue red green ```

Merge the elements of the `'red'` and `'blue'` levels into a new level labeled `'purple'`.

`colors = mergelevels(colors,{'red','blue'},'purple')`
```colors = 3x3 nominal purple purple green green purple purple purple purple green ```

Display the levels of `colors`.

`getlevels(colors)`
```ans = 1x2 nominal purple green ```

## Input Arguments

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Nominal or ordinal array, specified as a `nominal` or `ordinal` array object created with `nominal` or `ordinal`.

Levels to merge, specified as a string array, cell array of character vectors, or 2-D character array. For ordinal arrays, the levels in `oldlevels` must be consecutive.

Data Types: `char` | `string` | `cell`

Level to create from the merged levels, specified as a character vector or string scalar that gives the label for the new level.

Data Types: `char` | `string`

## Output Arguments

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Nominal or ordinal array, returned as a `nominal` or `ordinal` array object.

## Version History

Introduced in R2007a