I'm trying to tidy up and improve some of my code and have come across a loop that I am struggling to vectorise. I am calculating the mean value of specific parts of a matrix and replacing certain values within the matrix with the newly calculated values.
For example, if I have a matrix 'A' I would like to replace element A(3,1) with the mean of A(2,1) and A(3,1). Likewise, I would then like to replace A(3,2) with the mean of A(2,2) and A(3,2) and so on (although I don't want to do this for every single column, just specific ones). This process is also repeated at various other locations in the matrix (i.e. also replace A(6,1) with the mean of A(5,1) and A(6,1) and so on).
The looped version of my code is of the following form:
A = rand(7,6);
firstRows=[2;5];
lastRows=[3;6];
columnIndicies=[1 2 3];
A2=A;
for j=1:1:length(lastRows)
A2(lastRows(j),columnIndicies)= ...
mean(A((firstRows(j)):(lastRows(j)),columnIndicies),1);
end
A3 = A2(lastRows,:);
Any comments / assistance would be much appreciated.
