Ng-Zorro Table如何展示嵌套数组数据？

<code class="typescript">transformData(data: any[]): any[] {
  return data.map(item => ({
    func_code: item.func_code,
    func_name: item.func_name,
    frequency: item.frequency,
    high_frequency: item.high_frequency
  }));
}</code>

<code class="html"><table>
  <thead>
    <tr>
      <th>时间戳</th>
      <th>IP地址</th>
      <th>名称</th>
      <th nz-expand="" nzExpandable>报警信息</th>
    </tr>
  </thead>
  <tbody>
    <tr *ngFor="let item of data">
      <td>{{ item.timestamp }}</td>
      <td>{{ item.ip }}</td>
      <td>{{ item.name }}</td>
      <td>
        <ng-template nz-table-expand>
          <table *ngIf="item.alarm && item.alarm.length > 0">
            <thead>
              <tr>
                <th>功能代码</th>
                <th>功能名称</th>
                <th>频率</th>
                <th>高频率</th>
              </tr>
            </thead>
            <tbody>
              <tr *ngFor="let alarm of transformData(item.alarm)">
                <td>{{ alarm.func_code }}</td>
                <td>{{ alarm.func_name }}</td>
                <td>{{ alarm.frequency }}</td>
                <td>{{ alarm.high_frequency }}</td>
              </tr>
            </tbody>
          </table>
        </ng-template>
      </td>
    </tr>
  </tbody>
</table></code>

<code class="typescript">import { Component } from '@angular/core';

@Component({
  selector: 'app-my-table',
  templateUrl: './my-table.component.html',
  styleUrls: ['./my-table.component.css']
})
export class MyTableComponent {
  data: any[] = []; // 后端返回的数据

  constructor() {
    // 模拟后端数据
    this.data = [
      // ... your data ...
    ];
  }

  transformData = this.transformData;
}</code>