How to return value from one function within Function Matlab

Hello Everyone, I hope you are doing well.

I have create a function Stages, which take the prediction from model, bases on prediction the case statement is used to get the value from other functions e.g DFUNCTION,SFunction ,etc

I want to return the values for each case for example the case "Class 1" is selected , the function DFUNCTION run it should return [DValue,Dlength,dLevels,Dmaximum,Dminimum]

if case "Class 3" is selected it returns [SlidMaximum,SlidMinimum,Slidmeans]

but i am unable to do that

How can i do it in matlab

function [labels]=Stages(ImagePath)

I = imread(ImagePath);
im=imresize(I,[227 227]);
im = repmat(im,[1 1 3]);
Net=load('trainedmodel.mat');
label = classify(Net.trainedNet,im);
labels=string(label);
switch labels
    case  "Class 1"
        [DValue,Dlength,dLevels,Dmaximum,Dminimum] =DFUNCTION(ImagePath);
        
    case   "Class 2"
    [SLevels,SValue,SMinimum,SMaximum] =SFunction(ImagePath);
    case "Class 3"
       [SlidMaximum,SlidMinimum,Slidmeans] = SlidFunction(ImagePath);
    case "Class 4"
       [PMaximum,PMinimum,Pmeans]= PFunction(ImagePath);
    case "Class 5"
      [jMaximum,jMinimum,Jmeans] = JFunction(ImagePath);
    case "Class 6"
       [fMaximum,fMinimum,fmeans] = FFunction(ImagePath);
end

[Stephen john]

@Image Analyst @KSSV @Jan @Matt J

Answer 1

[Voss]

Returning different sets of outputs from the function Stages, depending on the value of label

% One way
function varargout = Stages(ImagePath)
I = imread(ImagePath);
im=imresize(I,[227 227]);
im = repmat(im,[1 1 3]);
Net=load('trainedmodel.mat');
label = classify(Net.trainedNet,im);
switch label
    case 'Class 1'
        [varargout{1:nargout}] = DFUNCTION(ImagePath);
    case 'Class 2'
        [varargout{1:nargout}] = SFunction(ImagePath);
    case 'Class 3'
        [varargout{1:nargout}] = SlidFunction(ImagePath);
    case 'Class 4'
        [varargout{1:nargout}] = PFunction(ImagePath);
    case 'Class 5'
        [varargout{1:nargout}] = JFunction(ImagePath);
    case 'Class 6'
        [varargout{1:nargout}] = FFunction(ImagePath);
end
end


% Another way
function varargout = Stages(ImagePath)
I = imread(ImagePath);
im=imresize(I,[227 227]);
im = repmat(im,[1 1 3]);
Net=load('trainedmodel.mat');
label = classify(Net.trainedNet,im);
lookup = { ...
    'Class 1' @DFUNCTION; ...
    'Class 2' @SFunction;  ...
    'Class 3' @SlidFunction; ...
    'Class 4' @PFunction; ...
    'Class 5' @JFunction; ...
    'Class 6' @FFunction};
[varargout{1:nargout}] = lookup{strcmp(lookup(:,1),label),2}(ImagePath);
end

[Stephen john]

@_ both are not working

the second method gives error

Intermediate brace '{}' indexing produced a comma-separated list with 0 values, but it must produce a single value when followed by subsequent indexing operations.

Error in Stages (line 15)

[varargout{1:nargout}] = lookup{strcmp(lookup(:,1),label),2}(ImagePath);

Related documentation

[Stephen john]

@_ The first method tell only number of arguments not values of arguments

[Walter Roberson]

What do you want your code to do if the function is run without any output arguments being requested?

.... I have a suspicion that you are hoping to run the function with no output assignments, and want it to assign to variables with those particular names anyhow. There are situations in which MATLAB would allow that to be done, but in most circumstances it should be avoided.

[Stephen john]

@Walter Roberson i want the output arguments as a variable . for example

if the labels has ouput

"Class 1" is selected , the function DFUNCTION run it should return [DValue,Dlength,dLevels,Dmaximum,Dminimum]

This values should be displayes on the main file

[Stephen john]

@Walter Roberson Then How can i get output variables/arguments of cases if one is true.

for example

case "Class 3"

[SlidMaximum,SlidMinimum,Slidmeans] = SlidFunction(ImagePath);

the output should return SlidMaximum,SlidMinimum,Slidmeans

[Voss]

@Stephen john The error you ran into is because the label wasn't one of 'Class 1' through 'Class 6' (maybe it was a string - I'm using character vectors here).

To the point of the original question: The different functions DFUNCTION, etc., return different numbers of outputs. And it is not known at the time Stages is called which of the functions DFUNCTION, etc., will be called within Stages since that is determined by the classification label of the input ImagePath, which is calculated within Stages.

The code that calls Stages cannot know whether Stages will return 3 outputs (in case the label is 'Class 3') or 5 (in case it's 'Class 1'), for instance, so one thing you can do is to modify the functions DFUNCTION, etc., to all return the same number of outputs by including some empty outputs. Then call Stages with that number of outputs.

Here is a simplified example:

% DFUNCTION called -> 5 outputs
[out1,out2,out3,out4,out5] = Stages(1)

out1 = 0

out2 = 1

out3 = 2

out4 = 3

out5 = 4

% SFunction called -> 4 outputs with 5th "dummy" output returned here
[out1,out2,out3,out4,out5] = Stages(2)

out1 = 5

out2 = 6

out3 = 7

out4 = 8

out5 =

     []

% SlidFunction called -> 3 outputs with 4th and 5th "dummy" outputs returned here
[out1,out2,out3,out4,out5] = Stages(3) 

out1 = 9

out2 = 10

out3 = 11

out4 =

     []


out5 =

     []

% SlidFunction called -> 3 outputs; only 3 outputs captured
[out1,out2,out3] = Stages(3) 

out1 = 9

out2 = 10

out3 = 11

% DFUNCTION called -> 5 outputs, but only 3 outputs are captured here
% the other 2 are lost. That's why you'd have every function return 5 outputs
[out1,out2,out3] = Stages(1)

out1 = 0

out2 = 1

out3 = 2

function varargout = Stages(ImagePath)
label = sprintf('Class %d',ImagePath);
switch label
    case 'Class 1'
        [varargout{1:nargout}] = DFUNCTION(ImagePath);
    case 'Class 2'
        [varargout{1:nargout}] = SFunction(ImagePath);
    case 'Class 3'
        [varargout{1:nargout}] = SlidFunction(ImagePath);
end
end


function [DValue,Dlength,dLevels,Dmaximum,Dminimum] = DFUNCTION(ImagePath)
DValue = 0;
Dlength = 1;
dLevels = 2;
Dmaximum = 3;
Dminimum = 4;
end
        
function [SLevels,SValue,SMinimum,SMaximum,out5] = SFunction(ImagePath)
SLevels = 5;
SValue = 6;
SMinimum = 7;
SMaximum = 8;
out5 = [];
end

function [SlidMaximum,SlidMinimum,Slidmeans,out4,out5] = SlidFunction(ImagePath)
SlidMaximum = 9;
SlidMinimum = 10;
Slidmeans = 11;
out4 = [];
out5 = [];
end