There are 4 shapes on a 6x6 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 (2, 4)
Distance from target shape to yellow square at (0, 2): 4
Distance from target shape to gray right_triangle at (1, 4): 1
Distance from target shape to brown rectangle at (0, 1): 5
Closest shape is the gray right_triangle at (1, 4) with distance 1</think>

<answer>(1, 4)</answer>