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, 2)
Distance from target shape to gray right_triangle at (0, 0): 5
Distance from target shape to brown trapezoid at (3, 1): 1
Distance from target shape to cyan trapezoid at (1, 2): 2
Closest shape is the brown trapezoid at (3, 1) with distance 1</think>

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