There are 6 shapes on a 7x7 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, 2)
Distance from target shape to pink rectangle at (0, 3): 4
Distance from target shape to red trapezoid at (2, 6): 5
Distance from target shape to green square at (3, 1): 1
Distance from target shape to brown square at (0, 6): 7
Distance from target shape to yellow square at (2, 1): 2
Closest shape is the green square at (3, 1) with distance 1</think>

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