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• Trials

## Mapping to Different Value Types

It is fairly common to store other classes, such as structures or cell arrays, in a Map structure. However, Maps are most memory efficient when the data stored in them belongs to one of the basic MATLAB® types such as double, char, integers, and logicals.

### Mapping to a Structure Array

The following example maps airline seat numbers to structures that contain information on who occupies the seat. To start out, create the following structure array:

```s1.ticketNum = '2S185'; s1.destination = 'Barbados';
s1.reserved = '06-May-2008'; s1.origin = 'La Guardia';
s2.ticketNum = '947F4'; s2.destination = 'St. John';
s2.reserved = '14-Apr-2008'; s2.origin = 'Oakland';
s3.ticketNum = 'A479GY'; s3.destination = 'St. Lucia';
s3.reserved = '28-Mar-2008'; s3.origin = 'JFK';
s4.ticketNum = 'B7398'; s4.destination = 'Granada';
s4.reserved = '30-Apr-2008'; s4.origin = 'JFK';
s5.ticketNum = 'NZ1452'; s5.destination = 'Aruba';
s5.reserved = '01-May-2008'; s5.origin = 'Denver';```

Map five of the seats to one of these structures:

```seatingMap = containers.Map( ...
{'23F', '15C', '15B', '09C', '12D'}, ...
{s5, s1, s3, s4, s2});
```

Using this Map object, find information about the passenger, who has reserved seat 09C:

```seatingMap('09C')
ans =
ticketNum: 'B7398'
reserved: '30-Apr-2008'
origin: 'JFK'```
```seatingMap('15B').ticketNum
ans =
A479GY
```

Using two Maps together, you can find out the name of the person who has reserved the seat:

```passenger = ticketMap(seatingMap('15B').ticketNum)
passenger =
Anna Latham
```

### Mapping to a Cell Array

As with structures, you can also map to a cell array in a Map object. Continuing with the airline example of the previous sections, some of the passengers on the flight have "frequent flyer" accounts with the airline. Map the names of these passengers to records of the number of miles they have used and the number of miles they still have available:

```accountMap = containers.Map( ...
{'Susan Spera','Carl Haynes','Anna Latham'}, ...
{{247.5, 56.1}, {0, 1342.9}, {24.6, 314.7}});
```

Use the Map to retrieve account information on the passengers:

```name = 'Carl Haynes';
acct = accountMap(name);

fprintf('%s has used %.1f miles on his/her account,\n', ...
name, acct{1})
fprintf('  and has %.1f miles remaining.\n', acct{2})

Carl Haynes has used 0.0 miles on his/her account,
and has 1342.9 miles remaining.
```