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Richie Cotton
Richie Cotton

Reputation: 121077

How do I convert strings to enumerations?

To convert an enumeration to be a character array is straightforward – you just call char.

char(myenum.somevalue)

returns 'somevalue'.

How do convert back again? I was expecting something like char2enum where

char2enum('somevalue', 'myenum')

returns myenum.somevalue.

Is there a builtin function for this or must I create my own?

Upvotes: 9

Views: 5176

Answers (3)

DeusExMachina
DeusExMachina

Reputation: 128

I know this question has been answered a long time ago, but I just found out about a different solution which can be pretty neat when using enums in an argument block. Also I couldn't find any reference to this feature in the official documentation so I thought I'd post it here:

The constructor for any enumeration can be called using an element name as sole argument. E.g.

>> Weekdays('Friday')
  
ans = 

  Weekdays enumeration

    Friday

Ok, so we can omit the dot. But why is this interesting? Well, when using enums as a function argument, the argument block allows for automatic conversion from string/char to enumeration.

function test(day)
    arguments
        day Weekdays
    end
    day
end

.

>> test('Friday')

day = 

  Weekdays enumeration

    Friday

Upvotes: 2

Nick Haddad
Nick Haddad

Reputation: 8937

You can use MATLAB Dynamic reference feature to access the enumeration by its name as a string instead of its symbolic name. For example, given a class Weekdays

classdef Weekdays
   enumeration
    Monday, Tuesday, Wednesday, Thursday, Friday
   end
end

You can access the Friday type in a couple of ways:

>> Weekdays.Friday  % Access symbolically

>> Weekdays.('Friday') % Access as a string

If you have a string variable with the name of the class that works too:

>> day = 'Friday'
>> Weekdays.(day)

BTW, this feature works for MATLAB Class methods, properties, and events, as well as struct fields.

http://www.mathworks.com/help/matlab/matlab_prog/bsgigzp-1.html#bsgigzp-33

Upvotes: 6

Jonas
Jonas

Reputation: 74940

Creating an enum from a character is also fairly straightforward: Just create the enumeration:

out = myenum.somevalue

returns out with class myenum and value somevalue.

If your string is in a variable, call

someVariable = somevalue;
out = myenum.(someVariable)

Upvotes: 5

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