how to acces matrix with some rows and columns

I have a large matrix and i want to access some rows and columns diagonally whose length varies at each iteration want to check sequence with in those rows and columns first and then have to check values outside those rows and columns but keeping track of main matrix as it is.

for example=A=[1 0 0 3 0 2;0 1 3 0 0 2;0 3 1 0 0 2;1 0 0 2 0 3;2 3 0 0 4 1;2 3 4 5 6 1;4 0 2 3 1 0]

i have to extract matrix like this,which are my cells

cell 1=[1 0;0 1]
cell 2=[1 0;0 2;0 0;4 5]
cell 3=[1 0]

all these are at diagonal now i want to check sequence of numbers with in these cells after that i want to acces the remaining part and check their sequnce in relation to numbers with in cells

[0 3 0 2]
[3 0 0 2]
[0 3 0 2] and so on

i hope someone gets what i really want to do.stuck in it since 2 weeks