Calling specific cells and averaging

Hello,

I have a 3000X3000 matrix. I also have a list of coordinates that I would like to use to indicate which values to select and average all the selected values. I can't seem to do it. I attached an example of a list.

Thank you for your time.

[Geoff Hayes]

Edward - please explain how the list of coordinates relates to the 3000x3000 matrix.

[Edward Lannon]

Sure thing. I would like to average values located in cells within a 3000X3000 matrix. These specific cells within the 3000X3000 do not follow any real pattern, so I constructed a list of coordinates that notes the location of each cell. So, basicaly the list attached has the locations coordinates (rows, colums) for 365 cells within the larged 3000X3000 matrix that I would like to aggragate and compute an average for.

Thanks for asking

Answer 1

[Hrishikesh Borate]

Hi,

I understand that you want to calculate average of elements present at indices stored in the file “VisualVisualTest.mat”. This can be done using following code:-

visualTest = load('VisualVisualTest.mat'); 
a = magic(3000); %3000x3000 matrix 
visualCordsall = visualTest.VisualVisualCordsall; 
indicesMatrix = transpose(reshape(cell2mat(visualCordsall),2,[])); 
sz = [3000, 3000]; 
ind = sub2ind(sz, indicesMatrix(:,1), indicesMatrix(:,2)); 
avgValue = mean(a(ind)); 

Where, avgValue stores the average value.

For more information, refer to sub2ind, cell2mat.

[Edward Lannon]

Thank you!