sudoku_main.py

start = '53..7....6..195....98....6.8...6...34..8.3..17...2...6.6....28....419..5....8..79'
    
rows = 'ABCDEFGHI'
cols = '123456789'
boxes = cartesian_product(rows, cols)

row_units = [cartesian_product(r, cols) for r in rows]
col_units = [cartesian_product(rows, c) for c in cols]
box_units = [cartesian_product(r,c) 
                    for r in ['ABC', 'DEF', 'GHI'] 
                    for c in ['123','456','789']]

unit_list = row_units + col_units + box_units

# each box(key) with its units(value)
unit_dict = dict((box, [unit for unit in unit_list if box in unit]) for box in boxes)
    
# each box with its peers
peer_dict = dict((box, set(sum(unit_dict[box], [])) - set([box])) for box in boxes)

# start string converted to dictionary
assert len(start) == 81
grid_dict = dict(zip(boxes, start))

# display unsolved board
display(grid_dict)
print('\n'*2)

# replacing the dots(.) with '123456789' (possible values in the box)
for k,v in grid_dict.items():
    if v == '.':
        grid_dict[k] = '123456789'

        
# =======================================================================
# Do all the testing and solving below this line
# =======================================================================

solved_grid = search(grid_dict)
# solved_grid = eliminate(grid_dict)


display(solved_grid)