How to find out the average of data gathered from a For Loop for a specific column in a table?

The script is finding out the mean pixel intensities in a ROI as well as other properties of sequential images in the folder.

I am trying to find out how to find the average of a certain column (meanGL) in the table T that is created from data gathered in the For Loop, this part of the code is not working. I am trying to find the average of the meanGL values.

% Creates table from For Loop Values with separate column for each variable
T.Properties.VariableNames={'numberOfPixels1' 'numberOfPixels2 ' 'meanGL'};
%Calculate the average meanGL for those specific layers
B = T(:,[3])
meanVal = mean(B,1)
% Name the file
filename='Thermal Imaging Data.xlsx'
% Write the data into named excel spreadsheet
writetable(T,filename,'Sheet',1,'Range','B2')

The whole script I am using is attatched.

Also if this average could also be displayed in the same excel spreadsheet as the rest of the data that would be wonderful?

[Bob Thompson]

What do you mean by 'the code is not working'? Are you receiving a specific error message, or how does your output differ from what you would expect?

From your question I'm guessing you are looking for a single average value of the mean results, but I would guess that your meanVal is giving you multiple results. Try removing the row-wise specifier from the mean command.

meanVal = mean(B);

[sebastian lim]

The code error that I get is:

Error using sum
Invalid data type. First argument must be numeric or
logical.

Error in mean (line 116)
        y = sum(x, dim, flag) ./ size(x,dim);

Error in Attempt_File3 (line 53)
meanVal = mean(B,1)

Yes that is correct i am trying to get a single average value of the mean results. But at the moment i just get this error.

Thank you for the help.

[Bob Thompson]

What is the class of B?

[sebastian lim]

Not 100% sure but i think its a column of just the meanGL values. And its a table.

Got it working now using the code:

meanVal = mean(T.meanGL,1);

This was what i was trying to achieve. Realise i didnt explain it very well.

Answer 1

[Peter Perkins]

The problem is that you are passing a table into mean. The table is a container, and what you need to do is to pass the variable in the table to mean. A one-variable table is not the same thing as the one variable.

You have variable names, you should use them!

meanVal = mean(T.meanGL,1);

There's more than one mean going on there, I guess, but I think that does what you are trying to do.

[sebastian lim]

Thank you very much, i understand the problem. That makes it much clearer! And yes that code is what i am trying to do. Your help is much appreciated.