Description of the Map Class

A Map is actually an object, or instance, of a MATLAB® class called Map. It is also a handle object and, as such, it behaves like any other MATLAB handle object. This section gives a brief overview of the Map class. For more details, see the containers.Map reference page.

Properties of the Map Class

All objects of the Map class have three properties. You cannot write directly to any of these properties; you can change them only by means of the methods of the Map class.

PropertyDescriptionDefault
CountUnsigned 64-bit integer that represents the total number of key/value pairs contained in the Map object.0
KeyTypeString that indicates the type of all keys contained in the Map object. KeyType can be any of the following: double, single, char, and signed or unsigned 32-bit or 64-bit integer. If you attempt to add keys of an unsupported type, int8 for example, MATLAB makes them double.char
ValueTypeString that indicates the type of values contained in the Map object. If the values in a Map are all scalar numbers of the same type, ValueType is set to that type. If the values are all character arrays, ValueType is 'char'. Otherwise, ValueType is 'any'.any

To examine one of these properties, follow the name of the Map object with a dot and then the property name. For example, to see what type of keys are used in Map mapObj, use

mapObj.KeyType

A Map is a handle object. As such, if you make a copy of the object, MATLAB does not create a new Map; it creates a new handle for the existing Map that you specify. If you alter the Map's contents in reference to this new handle, MATLAB applies the changes you make to the original Map as well. You can, however, delete the new handle without affecting the original Map.

Methods of the Map Class

The Map class implements the following methods. Their use is explained in the later sections of this documentation and also in the function reference pages.

MethodDescription
isKeyCheck if Map contains specified key
keysNames of all keys in Map
lengthLength of Map
removeRemove key and its value from Map
sizeDimensions of Map
valuesValues contained in Map

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