1D：声音，时间序列等；

2D：图像等；

3D：视频，高光谱图像等；

## 非欧几里得结构化数据

### 2. 非常见的欧几里得结构化数据

2D：生物网络(基因，分子，大脑连接)等；

3D：基础设施网络(eg：能源，交通，互联网，通信等)等；

## 图(Graph)

### 3. 图(Graph)的表示形式

#### 3.1 邻接矩阵( Adjacency matrix )

```+---+---+---+---+---+---+---+
|   | 1 | 2 | 3 | 4 | 5 | 6 |
+---+---+---+---+---+---+---+
| 1 | 0 | 1 | 0 | 0 | 1 | 0 |
+---+---+---+---+---+---+---+
| 2 | 1 | 0 | 1 | 0 | 0 | 0 |
+---+---+---+---+---+---+---+
| 3 | 0 | 1 | 0 | 1 | 0 | 0 |
+---+---+---+---+---+---+---+
| 4 | 0 | 0 | 1 | 0 | 1 | 1 |
+---+---+---+---+---+---+---+
| 5 | 1 | 0 | 0 | 1 | 0 | 0 |
+---+---+---+---+---+---+---+
| 6 | 0 | 0 | 0 | 1 | 0 | 0 |
+---+---+---+---+---+---+---+```

#### 3.2 度矩阵( Degree matrix )

```+---+---+---+---+---+---+---+
|   | 1 | 2 | 3 | 4 | 5 | 6 |
+---+---+---+---+---+---+---+
| 1 | 2 |   |   |   |   |   |
+---+---+---+---+---+---+---+
| 2 |   | 3 |   |   |   |   |
+---+---+---+---+---+---+---+
| 3 |   |   | 2 |   |   |   |
+---+---+---+---+---+---+---+
| 4 |   |   |   | 3 |   |   |
+---+---+---+---+---+---+---+
| 5 |   |   |   |   | 3 |   |
+---+---+---+---+---+---+---+
| 6 |   |   |   |   |   | 1 |
+---+---+---+---+---+---+---+```