[CLS 02 · 从类别到区域与掩码](/course/notebooks/f9ab632ba16b4f2084669791cba6ba85.html)

# 6. 活动：类别图与实例图怎样不同？ · 实现代码
[独立阅读](/course/notebook-blocks/a77753adddda4578b9601eba650283c3.html)
主线阅读与优先实验

同图四输出、共享计算、FCN、RoIAlign、信息碰撞与SAM接口
展开完整实现代码
```
# 独立 CPU 教学标签网格；不是照片真值或检测模型输出。
instance = [
 [0,0,0,0,0,0,0,0],
 [0,1,1,2,2,0,0,0],
 [0,1,1,2,2,0,0,0],
 [0,1,1,2,2,0,0,0],
 [0,0,0,0,3,3,3,0],
 [0,0,0,0,3,3,3,0]]
class_of = {0:0,1:1,2:1,3:2} # 类别0背景，1杯子，2书
semantic = [[class_of[x] for x in row] for row in instance]
boxes = {}
for identity in [1,2,3]:
    coordinates=[(r,c) for r,row in enumerate(instance) for c,x in enumerate(row) if x==identity]
    rows,cols=zip(*coordinates)
    boxes[identity]=(min(cols),min(rows),max(cols)+1,max(rows)+1)
print('实例图:'); [print(row) for row in instance]
print('语义图:'); [print(row) for row in semantic]
print('框(x0,y0,x1,y1；右/下边界不含):',boxes)
assert semantic[1][2]==semantic[1][3]==1
assert instance[1][2]!=instance[1][3]
```