Average across the fields of a structure when each field contains a single value

Hello,

I have a structure (Sway_dist_COP_Sag) with 3 fields, each containing a single value that I would like to average together. Please see image below. I would like the end result to be in the 2.15 range.

Thanks in advance.

Answer 1

[Voss]

S = struct('arbitrary',1.9623,'field',2.584,'names',1.9125)

S = struct with fields:
    arbitrary: 1.9623
        field: 2.5840
        names: 1.9125

C = struct2cell(S)

C = 3×1 cell array
    {[1.9623]}
    {[2.5840]}
    {[1.9125]}

result = mean([C{:}])

result = 2.1529

[Josh Tome]

Yes, this does seem to work for me. Interestingly though, when I try to combine your two lines of code into one...

result = mean([struct2cell(S){:}])

I get a "Invalid array indexing" error. Is there a reason I have to keep it 2 separate lines?

[Stephen23]

"Is there a reason I have to keep it 2 separate lines?"

Yes: in general MATLAB does not allow arbitrary trailing indexing.

Answer 2

[Image Analyst]

Try this

% Extract all values for each field into row vectors.
v1 = [Sway_dist_COP_Sag.Con1Pre00standop01]
v2 = [Sway_dist_COP_Sag.Con1Pre00standcl02]
v3 = [Sway_dist_COP_Sag.Con1Pre00stand05_1plate]
% Take the mean of all 3 row vectors strung together.
theMean = mean([v1, v2, v3])

[Josh Tome]

As I use this in the future, the name of the structure will be the same, but the field names will be different. Is there a way to account for that?

[Image Analyst]

You can use fieldnames and dynamic field names. Something like

fn = fieldnames(Sway_dist_COP_Sag);
for k = 1 : numel(fn)
    thisFieldName = fn{k};
    v1 = Sway_dist_COP_Sag.(thisFieldname)
end

[Josh Tome]

Won't the for loop continously make v1 equal to whatever the current fieldname's value is?

Also, sorry to complicate things further, but I forgot to mention that I may in the future have more (or less) than three fields.

[Voss]

"Won't the for loop continously make v1 equal to whatever the current fieldname's value is?"

Yes.

Take a look at my answer and see if it'll work for your purposes.