Question

I am trying to reference an element buried within a structure that I did not create (hence I don’t know the exact way in which it was built).

Having loaded the structure, if I type:

dataFile.RECORDINGS.eye

I receive the following output:

ans =

    2


ans =

    2

Both of those variables will always be the same, but they could be at any time 1, 2 or 3. What I’d like to do is check with a switch statement which looks like this:

switch dataFile.RECORDINGS.eye
    case {1, 2}
        % action A
    case 3
        % action B
end

Of course, the above throws up an error because ‘case’ cannot check whether dataFile.RECORDINGS.eye contains a given value since there are two elements stored under that address. So, my question is: how do I reference just one of the elements? I thought it would be as simple as replacing the first line with:

switch dataFile.RECORDINGS.eye(1)

…But, this gives the error:

??? Field reference for multiple structure elements that is followed by more reference blocks is an error.

Similarly, I can’t access the element like this:

switch dataFile.RECORDINGS.eye.1

…As I get the following error:

??? Dot name reference on non-scalar structure.

Answer 1

If the values are really always the same, you can try the following to get a scalar that can be used in the switch command:

unique([dataFile.RECORDINGS.eye])

By the way, did you try to index RECORDINGS, i.e.,

dataFile.RECORDINGS(1).eye   
dataFile.RECORDINGS(2).eye