Convert from struc to a .mat file

Hello all!

Please help me!I have a problem and I found no solution!!

I have my file.mat. I used 'WS=whos('-file', FileName)' to save my file as a structure. Now i need to add new variables in my structure and after that to convert my new structure back in a .mat file.

I tried to use: 'save ('file.mat', '-struct', 'WS')' but it gives me this error: '??? Error using ==> save The argument to -STRUCT must be the name of a scalar structure variable.'

Waiting for your help... Thanks

Answer 1

[Walter Roberson]

WS = whos('-file', FileName)

does not save the file as a structure: it only gets you the names and other information about the variables that are stored in the files, without getting their values.

The information returned by whos() is a structure array, one element per variable in the file. This conflicts with the requirement of save -struct that "the argument to -STRUCT must be the name of a scalar structure variable" (emphasis added). WS is not a scalar structure variable.

If you are wanting to load your file as a structure then you should use

WS = load(FileName);

This will be a scalar structure array, with one field for each variable name in the file. You can use fieldnames(WS) to find the names of the variables.

[Diana Acreala]

Ok! I understand! But is there a solution for solving my problem without using 'WS = load(FileName);'?

At this point this requires to change more code...

[Walter Roberson]

As I indicated, the whos() does not load the _content_ of any of the variables. Are you certain that you want to create the .mat file without ever having looked at the actual content of the old one?

But if you really need it, here is code that will convert the non-scalar structure array WS to the scalar structure array WS2 with each WS(K) becoming a field in WS2 named according to WS(K).name

for K = 1 : length(WS)

WS2.(WS(K).name) = WS(K);

end

save('file.mat', '-struct', 'WS2')

Practical uses for this do not seem immediately obvious to me...

[Diana Acreala]

GREAT! Now it's working:) Thank you!

Have a nice day!:D