Pass variable name through variable of a custome save function made error

Hello guy

I am making a custom save function. I tried declare the variable name, file name first in the script then pass them to my custom save function. However when do that the save function in my custom function return error.

Error using save
The argument to -STRUCT must be the name of a scalar structure variable.

But if I call save function with the same declared variables like before, it work. Here is my code. The saveModel function is my custom function. I removed it by the comment line. Thank for your help.

folderName = "E:\KLTN\trained_model\gait_regression"
modelName = "knee_toruqe_trainedModel"

fileName = folderName + "\" + modelName + ".mat"
%saveModel(fileName,modelName)
save(fileName,"-struct",modelName)
function saveModel(file,model)
    save(file,"-struct",model)
    disp("Save model")
    disp(model)
    disp("as file")
    disp(file)
end

Answer 1

[Voss]

In saveModel, the variable model is a string variable containing the name of the struct variable you want to save, right?

The problem is that struct variable doesn't exist in the saveModel workspace. It exists in the workspace where saveModel is called from.

One solution is to use evalin("caller",_) to pop the same struct variable into existence in the saveModel workspace:

modelName = "knee_toruqe_trainedModel"
saveModel(fileName,modelName)

function saveModel(file,model)
    S = evalin("caller",model);
    save(file,"-struct","S")
end

A better solution is just to pass the actual struct to saveModel and have it save based on that:

saveModel(fileName,knee_toruqe_trainedModel)

function saveModel(file,model)
    save(file,"-struct","model")
end

[Tran Tran]

Thank you, it work. Your idea is that the variable i pass to save function doesn't exist in scope of the custom save function (saveModel) was right. When use evalin like you suggest it work like I want. I evalin the variable from "base" instead of "caller" and it still work.

function saveModel(file,model)
    pass = evalin("base",model)
    save(file,"-struct","pass")
    disp("Save model")
    disp(model)
    disp("as file")
    disp(file)
end

[Voss]

You're welcome!

[Stephen23]

“I evalin the variable from "base" instead of "caller" and it still work.”

Using caller is correct, as Voss showed.

Answer 2

[Steven Lord]

When you call this code, what does this command show?

whos knee_toruqe_trainedModel

If it shows nothing, try with the correct spelling of the word "torque".

whos knee_torque_trainedModel

I want to see if this is a 1-by-1 struct array.