Calculations for arrays inside an array

I have a 1x1 structure with 6 fields. In each field is a cell array comprised of various lengths x 8 columns. I would like to write a loop that will perform a specific calculation for EACH cell array i.e.) subtract column 5 from 4, then compute the average.

I can't seem to get the loop going, I keep getting errors such as "Cell contents reference from a non-cell array object. ".

Any suggestions are greatly appreciated.

[Andrei Bobrov]

Where is your example? Please attach an example of your structure, as a mat-file.

Answer 1

[dpb]

Making the array content cell arrays complicates dereferencing but something like

structfun(@(c) mean(c{:}(:,5)-c{:}(:,4)),s)

works for specific column indices.

The above assumes the structure is like

>> s.f1={rand(3,4)};
>> s.f2={rand(5,4)}
s = 
struct with fields:
  f1: {[3×4 double]}
  f2: {[3×4 double]}
>>

There's no reason that the struct needs the arrays as cell arrays, though, each field content is independent so you can have differing-sized double arrays and use direct addressing --

>> s.f1=rand(3,4);
>> s.f2=rand(5,4)
s = 
struct with fields:

    f1: [3×4 double]
    f2: [5×4 double]
>>

Then, it's just

structfun(@(c) mean(c(:,5)-c(:,4)),s)

as structfun pass each field in turn which is now just a double array instead of cell containing a double array.

Of course, if your structure is some other perturbation, we'll need to know what that is to know how to dereference it properly.

[Andrei Bobrov]

+1