Using structures as enum input to a function in MATLAB
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Hello
I'm implementing a function that gets as one input with two possible values Red (enum configured as 1) , Green(enum configured as 2).
so what I did in matlab is this:
colors = struct('Red', 1, 'Green', 2);
function output=choose(colors)
{
if (colors == Red) %in other words if I input 'Red' to function choose
do something
else (colors == Green )%in other words if input is 'Green' to function choose
do something
}
So I want to write this, choose (Red) or choose(Green) and get the required output of a function. this means I want to write in my editor after building the function just this : choose(Red) or choose (Green) then I get output.
How I can implement that in matlab? as I showed above it tells me once I write choose(Red) that Red isn't defined although I already defined it as structure above the function... any help?!
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Answers (1)
Jan
on 22 Dec 2020
You have defined a struct, but this is not an enum. With your code (if you omit the curly braces), you could use:
choose(colors.Red)
becaus your have created a struct. Matlab cannot guess, that you want to treat the field names for another purpose.
You need to defined an enumeration class for an enumeration: doc enumeration
Even then you need to sepcify the enumeration class in addition and choose(Red) is not possible:
classdef colors
enumeration
Red, Green
end
end
choose(colors.Red)
7 Comments
Jan
on 23 Dec 2020
@Jimmy cho: I strongly recommend not to do that and I do not believe that this is a clean programming style, but it works easily:
Insert in each function, which uses the variables, these lines:
Red = 1;
Green = 2;
Alternatively create a script, which contains these lines und call it from each function before the variables are used. Then you have to change only one code, if you add a new color. Remember, that this can slow down the processing massively, because the JIT-accelerator might not know the type of the concerned variables. Therefore I'd never use a script for anything.
The clean way is to define an enumeration class and "color.red" instead of "Red". I cannot imagine, why this clean and efficient method does not satisfy your needs and why choose(Red) is so much better then e.g. choose('red') .
per isakson
on 24 Dec 2020
Why not
classdef colors < uint8
enumeration
Red (1)
Green (2)
end
end
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