How do I "use structures for function arguments"?

Question

Leslie 2019-5-23

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/463569-how-do-i-use-structures-for-function-arguments

编辑： per isakson 2019-5-23

采纳的回答： per isakson

在 MATLAB Online 中打开

The MATLAB Stye Guidelines 2.0 (Johnson 2014) contains the following advice:

Use structures for function arguments.

Usability of a function decreases as the number of arguments grows, especially when some arguments are optional. Consider using structures whenever arguments lists exceed three.

Structures can allow a change to the number of values passed to or from the function that is compatible with existing external code.

Structures can remove the need for arguments to be in fixed order. Structures can be more graceful for optional values than having a long and ordered list of variables.

-----

I don't know how to implement this advice!

If I have

function [y1,y2] = myfun(x1,x2,text1,cmap1,cmap2,cmap3,cmapA,...
                         cmapH,text2,x3,x4,x5)
end

how do I put all those real variables (x's), integer arrays of various dimensions, character arrays, etc. into a structure?

How would doing this "allow a change to the number of values passed" or "remove the need for arguments to be in a fixed order"?

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Answer 1

per isakson 2019-5-23

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/463569-how-do-i-use-structures-for-function-arguments#answer_376252

编辑：per isakson 2019-5-23

在 MATLAB Online 中打开

Try this

S.x1     = 17   ;
S.x2     = 18   ;
S.text1  = 'ABC';
S.cmap1  = magic(3);
S.cmap2  = magic(3);
S.cmap3  = magic(3);
S.cmapA  = magic(3);
S.cmapH  = magic(3);
S.text2  = 'DEF';
S.x3     = 19   ;
S.x4     = 20   ;
S.x5     = 21   ;
%
[y1,y2] = myfun( S );
%
function [y1,y2] = myfun( S )
    if not( isfield( S, 'cmapB' ) )
        S.cmapB = rand(3); % default value
    end
    y1 = S.x1;
    y2 = S.x2;
end