How do you iterate over multiple fields in a structure?

I have a 1X1 struct with 48 fields in it. Each field is 1X5120 int 32. I want to downsample each of these fields using the downsample(y, n) function.

However, I would like to accomplish this using a loop. How can it be done?

[Stephen23]

You could make this task easier by improving the data design.

Numbered fieldnames (or variable names) like that is usually a sign that you are doing something wrong.

Rather than forcing meta-data (e.g. pseudo-indices) into the fieldnames like you are doing, your data would be much better stored in a non-scalar structure or a simple cell array. Then you can use basic indexing to loop over the data.

Answer 1

[Stephen23]

One approach is to use FIELDNAMES() and dynamic fieldnames:

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

For example, where S is your scalar structure:

n = 5;
C = fieldnames(S);
for k = 1:numel(C)
    F = C{k};
    A = S.(F);
    B = downsample(A,n);
    S.(F) = B;
end

Another simple option is to use STRUCTFUN():

https://www.mathworks.com/help/matlab/ref/structfun.html

For example:

n = 5;
fnh = @(v) downsample(v,n);
S = structfun(fnh, S)