How can I select a specific variable in the .mat file which contains different variables in the user interface?

Hi! I want to design an app which can draw with a .mat file. How can I select a specific variable in the .mat file which contains different variables in the user interface? By 'text area' or something?

Answer 1

[Fangjun Jiang]

1. Use load() with return structure.

gongStruct = load('gong.mat'); 
fieldnames(gongStruct)

1. Use matfile object.

Help matfile

Answer 2

[Cam Salzberger]

Hello Kunpeng,

You may consider using whos to determine the variables available in a MAT file. Then you can specify the variable you want when you call load based on the user selection. This will be faster than loading the entire MAT file into the workspace, unless you expect the user to frequently switch between what they want loaded.

You may also consider checking out the matfile object, as Fangjun suggested.

-Cam

[Kunpeng Zhang]

Thanks! That's a new way. I'll try it!

[Kunpeng Zhang]

Hi Cam . I wonder how to implement that allows users to select special variables in the GUI surface to participate in the operation. By typing the name of variable in the text area or by other components? Thanks!

[Kunpeng Zhang]

I have solved this problem with eval() function!

[Stephen23]

"I have solved this problem with eval() function!"

A much better** solution is to load into an output variable, just like Fangjun Jiang's Answer shows, and then access its fields:

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-structure-array.html

https://www.mathworks.com/help/matlab/matlab_prog/generate-field-names-from-variables.html

** better in the sense faster, more efficient, more robust, less buggy, much easier to debug. The approach you are using is not recommended:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

[Kunpeng Zhang]

Wow，that is awesome！！！I will study and try alternative methods. Thank you for your advice！！