I have a 3 dimensional array (10x3x3) in Matlab and I want to change any value greater than 999 to Inf. However, I only want this to apply to (:,:,2:3) of this array.
All the help I have found online seems to only apply to the whole array, or 1 column of a 2D array. I can't work out how to apply this to a 3D array.
I have tried the following code, but it becomes a 69x3x3 array after I run it, and I don't really get why. I tried to copy the code from someone using a 2D array, so I just think I don't really understand what the code is doing.
A(A(:,:,2)>999,2)=Inf;
A(A(:,:,3)>999,3)=Inf;
One approach with logical indexing -
mask = A>999; %// get the 3D mask
mask(:,:,1) = 0; %// set all elements in the first 3D slice to zeros,
%// to neglect their effect when we mask the entire input array with it
A(mask) = Inf %// finally mask and set them to Infs
Another with linear indexing -
idx = find(A>999); %// Find linear indices that match the criteria
valid_idx = idx(idx>size(A,1)*size(A,2)) %// Select indices from 2nd 3D slice onwards
A(valid_idx)=Inf %// Set to Infs
Or yet another with linear indexing, almost same as the previous one with the valid index being calculated in one step and thus enabling us a one-liner -
A(find(A(:,:,2:3)>999) + size(A,1)*size(A,2))=Inf