Check if a field within a structure exist

I have a structure with data for different periods (9) of a timeseries. Sometimes within a structure there's a field called "Breaks". e.g. Data.Period_4.Breaks, whicjh contains 2 duration values. I need to check for each period (1:9) if the field Breaks exist. However when doing the following below, it does always provide "false". Am I missing something or not doing properly? Also, can I use "~isfield"... it does not say no when used.

for i=1:9

chunk = strcat('Period_',num2str(i));

if isfield(strcat('Data.',chunk),Breaks)

data = xyz;

elseif ~isfield(strcat('Data.',chunk),Breaks)

data =zyx;

end

Regards

Eduardo

[Stephen23]

"Am I missing something..."

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

Answer 1

[Voss]

for i=1:9
    chunk = sprintf('Period_%d',i);
    if isfield(Data.(chunk),'Breaks')
        data = xyz;
    else
        data = zyx;
    end
end