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I have a tensor of size

h=[:,:, 8,8,: ]

The way that I see the tensor is that it is formed by 8 x 8 elements. If we assume periodic boundaries, I want to extract the boundaries of each element,

Let's say that h=[:,:,i,j,:]

I have written the next code:


for i in range(8):
    for j in range(8):

        row_start = i-1 if i > 0 else 7
        row_end = i+1 if i < 7 else 0
        col_start = j-1 if j > 0 else 7
        col_end = j+1 if j < 7 else 0

# Extract the submatrix containing the boundaries

        boundaries = h[:,:, row_start:row_end+1, col_start:col_end+1,:]

    # Check if the boundaries extend beyond the edges of the matrix

        if i == 7:
            # Add the top row of the matrix to the top of the boundaries

            top_row = h[:,:,0,  col_start:col_end+1,:]
            top_row = top_row[:,np.newaxis,:,:,:]
            boundaries = torch.vstack([boundaries, top_row])

        if i == 0:

            # Add the bottom row of the matrix to the bottom of the boundaries

            bottom_row = h[:,:,-1,  col_start:col_end+1,:]
            bottom_row = bottom_row[:,np.newaxis,:,:,:]
            boundaries = torch.vstack([boundaries, bottom_row])

        if j == 7:

            # Add the leftmost column of the matrix to the left of the boundaries
            left_col = h[:,:,row_start:row_end, 0,:]
            right_col = torch.unsqueeze(right_col, 1)
            boundaries = torch.hstack([boundaries, left_col])   

        if j == 0:

            # Add the rightmost column of the matrix to the right of the boundaries
            right_col = h[:,:,row_start:row_end, -1]
            right_col = torch.unsqueeze(right_col, 1)
            boundaries = torch.hstack([boundaries, right_col])       

What I have tried:

The code is facing problems to extract the boundaries. Any ideas please. Is this code correct?
Updated 16-Feb-23 11:34am
Richard MacCutchan 17-Feb-23 3:47am    
"The code is facing problems"
Then you need to explain exactly what thos problems are. Please use the Improve question link above, and add complete details of what is not working.

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