Python: Forming overlapping matrix of 3*3 using 9*9 matrix - python-2.7

Question

I am trying to create a neighborhood of pixel by using pixel matrix. The pixel matrix is the matrix of pixels in a 1 band image. Now I have to form matrix of 3*3 keeping each element of 9*9 matrix at center and have a neighbor for each element. Thus the element at (0,0) position will have neighboring elements as
[[0 0 0],
[0 2 3],
[0 3 4]]
Same case will happen to all elements in the first and last row and column. Attached image can help understanding better.
So the resultant matrix will have the size of 81*81. It is not necessary to save the small matrix in the form of matrix.
I have tried below,
n = size[0]
z= 3
x=y=0
m =0
while all( [x<0, y<0, x>=n, y>=n]):
continue
else:
for i in range(0, n):
arcpy.AddMessage("Hello" )
for x in range(m,m+3):
temp_matrix = [ [ 0 for i in range(3) ] for j in range(3) ]
for y in range(m,m+3):
temp_matrix[x][y] = arr_Pixels[x][y]
m+=1
y+=1
temp_List.append(temp_matrix)
But I am getting error: list assignment out of index. Also it looks too lengthy and confusing. I understood the error is occurring because, there is no increment in the array temp_matrix length.
Is there any better way to implement the matrix in image? Smaller matrices can be saved into list rather than matrix. Please help me.
Update #2
n = size[0]
new_matrix = []
for i in range(0,n):
for j in range(0,n):
temp_mat = [ [ 0 for k in range(3) ] for l in range(3) ]
for k in range(i-1, i+2):
for l in range(j-1,j+2):
if any([k<0, l<0, k>n-1, l>n-1]):
temp_mat[k][l] = 0
else:
temp_mat[k][l] = arr_Pixels[k][l]
new_matrix.append(temp_mat)

Answer 1

I think one issue is your use of while/else. The code in else only executes after the while condition is true and the while will not repeat again. This question might be helpful.
Thus, once it enters else, it will never check again that x<=n and y<=n, meaning that x and y can increase beyond n, which I assume is the length of arr_Pixels.
One better way to do it would be to create two nested for loops that increment from 0 to n and create the temp neighborhood matrices and add them to the 9x9 matrix. Here is an rough outline for that:
new_matrix = [] //future 9x9 matrix
for i in range(0, n):
for j in range(0, n):
// create a neighborhood matrix going around (i, j)
// add temp matrix to new_matrix
This method would avoid having to check that the indexes you are accessing are less than n because it assures that i and j will always be less than n-3.

Answer 2

I found better way of doing it by padding the whole matrix by zero. Thus it resolves the negative indexing problems.
matrix can be padded as
pixels = np.pad(arr_Pixels, (1,1), mode='constant', constant_values=(0, 0))
It adds rows and columns of zeros along the axes.