Accessing structure by its name and looping through it

Hi,

I'm wondering how I can access a structure by its upper level name from a cell array, and loop through it. For example:

Tests = {'Cold Run'
         'Warm Run'
         'Hot Run'};
for I = 1:length(Tests)
    plot(Tests{I}.Time,Tests{I}.Speed);
    hold on;
end

Tests{I} is wrong. If it was part of a larger structure, say "Something", then this would work:

Something.(Tests{I}).Time

But what is the proper syntax to do this without an upper structure?

[Guillaume]

Your question is really not clear. In your example Tests is a cell array containing char vectors. There is no structure anywhere.

[Eric Christensen]

Oops. Forgot to include the array definitions that appear above the Tests cell array.

The structures would look something like:

Cold_Run.Time = data1;
Cold_Run.Speed = data2;
Warm_Run.Time = data3;
Warm_Run.Speed = data4;
Hot_Run.Time = data5;
Hot_Run.Speed = data6;

And the corrected Tests cell array would be:

Tests = {'Cold_Run'
         'Warm_Run'
         'Hot_Run'}

I suppose my question is, how can I loop through the 3 structures and access data from them throughout the loop?

[Guillaume]

Do you mean:

Tests = {Cold_Run, Warm_Run, Hot_Run};  %cell array containing structures

as opposed to a cell array containing char vectors which happen to be the name of some variables.

[Eric Christensen]

Ah yes, I overcomplicated it by creating that cell array just to have the names to loop through. That seems to work, thanks.

[Stephen23]

Reagrding the original question: you should read this:

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

Matt J's suggestion to use a structure array is better than using a cell array of scalar structures:

https://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html

Answer 1

[Matt J]

Why not organize the data as a struct array?

Tests(1).Time = data1;
Tests(1).Speed = data2;

Tests(2).Time = data3;
Tests(2).Speed = data4;

Tests(3).Time = data5;
Tests(3).Speed = data6;

The indexing of the different scalar structures Tests(j) is now immediate.