There are 4 shapes on a 4x4 grid. Which shape is closest to the purple square in terms of Manhattan distance? The final answer is the grid position of the closest shape like (row_index, column_index).
<think>Target shape: purple square at (3, 3)
Distance from target shape to red rectangle at (1, 3): 2
Distance from target shape to blue rectangle at (3, 2): 1
Distance from target shape to yellow square at (2, 2): 2
Closest shape is the blue rectangle at (3, 2) with distance 1</think>

<answer>(3, 2)</answer>