So I am trying to use bilinear interpolation to extrapolate data for certain values of a 3-dimensional array. But, the issue is that the bilinear interpolation requires an input of the 4 closest numbers by distance in order for the equations to be solved. Does anyone have an idea of how I can obtain these 4 values. I am going to put some context below for better understanding.
62 0 63 0
0 0 0 0
63 0 61 0
0 0 0 0
I am going to refer to the coortinates of the elements in the form of (row,column).
So for example, consider this array above. For context, I need a way to find the 4 closest non-zero points to (1,2). If I solved this manually, the points would be (1,1),(1,3),(3,1),(3,3).
This is only a small part of a very large array that I have given for context. If anyone can help me with the coding, it would be appreciated.