How to use varargin names to specify values

I want to be able to use varargins like plot does, where you have to write the variable name for the variable being specified before defining a value for it, e.g.

plot(x, y, '--rs', 'LineWidth', 4, 'MarkerSize', 10, 'MarkerEdgeColor', 'b')

where 'LineWidth', 'MarkerSize' and 'MarkerEdgeColor' are the variables being changed and 4, 10 and 'b' are the values being assigned to these variables.

I want to know how they do this, so I can implement it into my own code. Is it just a case of doing

 if(~isempty(varargin))
     for i = 1:size(varargin, 2) - 1
         if(strcmp(varagin{i}, 'LineWidth')
             LineWidth = varargin{i+1};
         elseif(strcmp(varargin{i}, 'MarkerSize')
             MarkerSize = varargin{i+1};
         elseif(strcmp(varargin{i}, 'MarkerEdgeColor')
             MarkerEdgeColor = varargin{i+1};
         end
     end
 end

or is there a simpler way of doing this? The above method feels really clunky and long winded, so having a quicker method would be ideal.

[Stephen23]

"The above method feels really clunky and long winded"

It is clunky, and it will not expand easily, for the reasons explained here: https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

"or is there a simpler way of doing this?"

See my FEX submission num2words for one example of how to do this. I convert the varargin into a structure (this is trivial using struct), and then parse that structure, providing default values where required.

MATLAB also has an input parser that you can use, but in my experience it is quite slow.

Answer 1

[Walter Roberson]

See https://www.mathworks.com/help/matlab/ref/inputparser-class.html

[Daniel]

Thank you