There are 6 shapes on a 4x4 grid. Which shape is closest to the purple right_triangle 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 right_triangle at (3, 3)
Distance from target shape to red right_triangle at (0, 2): 4
Distance from target shape to green right_triangle at (2, 0): 4
Distance from target shape to orange trapezoid at (3, 1): 2
Distance from target shape to blue right_triangle at (3, 0): 3
Distance from target shape to yellow trapezoid at (2, 2): 2
Closest shape is the orange trapezoid at (3, 1) with distance 2</think>

<answer>(3, 1)</answer>