MATLAB Programming Fundamentals - MathWorks

Description of 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 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.

Property Description Default

Count Unsigned 64-bit integer that represents the total number of

key/value pairs contained in the Map object.

0

KeyType Character vector 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

ValueType Character vector 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.

14 Map Containers