MATLAB: Average of several (different, across) structures

meanstructure

I have 10 structures with 6 fields, each with 3D arrays. All of them have the same organization.
I want to do the average of the 10 structures, as a result I would have 1 mean structure with 6 fields, each with 3D arrays.
For example, I have:
Subject_1_RMSE_angle = 
  struct with fields:
    narxwalk: [17×10×16 double]
     EMGwalk: [17×10×16 double]
      narxup: [17×10×16 double]
       EMGup: [17×10×16 double]
    narxdown: [17×10×16 double]
     EMGdown: [17×10×16 double]
     
 Subject_2_RMSE_angle = 
  struct with fields:
    narxwalk: [17×10×16 double]
     EMGwalk: [17×10×16 double]
      narxup: [17×10×16 double]
       EMGup: [17×10×16 double]
    narxdown: [17×10×16 double]
     EMGdown: [17×10×16 double]
     
  Subject_3_RMSE_angle = 
  struct with fields:
    narxwalk: [17×10×16 double]
     EMGwalk: [17×10×16 double]
      narxup: [17×10×16 double]
       EMGup: [17×10×16 double]
    narxdown: [17×10×16 double]
     EMGdown: [17×10×16 double]
then do the mean, and have a results as:
Subject_MEANs_RMSE_angle = 
  struct with fields:
    narxwalk: [17×10×16 double]
     EMGwalk: [17×10×16 double]
      narxup: [17×10×16 double]
       EMGup: [17×10×16 double]
    narxdown: [17×10×16 double]
     EMGdown: [17×10×16 double]
Thank you.

Best Answer

Fake data in scalar structures:
S1 = struct('A',randi(99,4,3,2),'B',randi(99,4,3,2));
S2 = struct('A',randi(99,4,3,2),'B',randi(99,4,3,2));
S3 = struct('A',randi(99,4,3,2),'B',randi(99,4,3,2));
Concatenate into one non-scalar structure (which they should be anyway):
SX = [S1,S2,S3];
Concatenate data from each field, calculate mean:
C = fieldnames(SX);
SZ = struct(); % scalar structure
for k = 1:numel(C)
    F = C{k};
    SZ.(F) = mean(cat(4,SX.(F)),4);
end
SZ is a scalar output structure containing the means of the input scalar structures.
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