Various inputs and outputs in functions

Asked by Jason on 9 Sep 2017

Latest activity Edited by José-Luis on 9 Sep 2017

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Hi. I have several techniques to find spots on an image and rather than have say 5 different functions I want to create one and pass in a "method" flag. My question is that each different method has a different number of inputs and outputs. Im not sure how to handles these, and help is greatly appreciated.

function[p1,p2,p3,p4,p5]=objectDetections(handles,image,x,y,par1,par2,method)
   if method==1
     //perform method 1 - requires inputs handles,image,x,y
     // returns p1,p2
   elseif method==2   
     //perform method 2 - handles,image,x,y, par1
     //returns p1,p3
   elseif method==3   
     //perform method 3 - handles,image,x,y, par1, par2
     //returns p1,p2,p3,p4,p5
   end

1 Comment

Stephen Cobeldick on 9 Sep 2017

The simplest, clearest, neatest solution: use a structure. This is what MATLAB uses for many advanced functions that support multiple options, (e.g. optimization, ODE's, etc), and is simple to implement.

2 Answers

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Answer by KSSV on 9 Sep 2017

Edited by KSSV on 9 Sep 2017

Accepted Answer

You have multiple options...one of the option is make output a structure....

function[out]=objectDetections(handles,image,x,y,par1,par2,method)
   if method==1
     //perform method 1 - requires inputs handles,image,x,y
     out.p1 = p1;
     out.p2 = p2;
   elseif method==2   
     //perform method 2 - handles,image,x,y, par1
     out.p1=p1;
     out.p3=p3;
   elseif method==3   
     //perform method 3 - handles,image,x,y, par1, par2
     out.p1=p1;
     out.p2=p2;
     out.p3=p3;
     out.p4=p4;
    out.p5=p5;
end

You can also make output a cell.

3 Comments

Jason on 9 Sep 2017

Thats a nice idea. What about for the input arguments, for example method 1 doesn't require par1 or par2, can I just use a ~ i.e.

objectDetections(handles,image,x,y,~,~,method) or is there a nicer way?

Thanks

KSSV on 9 Sep 2017

Input also can be made a structure

Jason on 9 Sep 2017

Thankyou

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Answer by José-Luis on 9 Sep 2017

Edited by José-Luis on 9 Sep 2017

You could pass a structure to your function. The structure could contain whatever flags and arguments you need. Same goes for the output.

Slightly more cumbersome: a function can accept a variable number of arguments -> varargin

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