Arrays 在ngFor中合并两个数组

我从服务中获得了两个阵列a：

handleProjectLoaded(project){

    this.projectService.getCodesByType( "Structure" ).subscribe( response => {

        this.structures = response;
    });

    this.projectService.getCodesByType( "Direction" ).subscribe( response => {

        this.lines = response;
    });
}

一个数组在结构中，第二个数组在行中。我有他们在html单独和ngFor显示

<div class="div-width-button3">
    <select #lineSelect class="custom-select custom-select-project" style="flex-basis:49%" (change)="addDirection(directionSelect.value); directionSelect.selectedIndex = 0;">
        <option selected disabled value="">Add a direction</option>
        <option *ngFor="let direction of directions" [value]=direction.id
            [selected]="direction.id==directionSelect.value">{{direction.name}}</option>
    </select> 
    <select #structureSelect class="custom-select custom-select-project"  style="flex-basis:49%"
        (change)="addStructure(structureSelect.value); structureSelect.selectedIndex = 0;">
        <option selected disabled value="">Add a structure</option>
        <option *ngFor="let structure of structures" [value]=structure.id
            [selected]="structure.id==structureSelect.value">{{structure.name}}</option>
    </select>
</div>

添加方向
{{direction.name}
添加一个结构
{{structure.name}

---

我需要一个解决方案来将这两个阵列显示为一个阵列和一个ngFor。有什么方法可以合并它们吗？

我没有测试它，但是为什么不使用concat呢

{{line.name}}

==编辑===

事实上，我改变了主意，因为我认为我上一个例子中的structuresAndLines是一个2d数组。因此，请尝试以下方法：

handleProjectLoaded(project){

  Observable.zip(
    this.projectService.getCodesByType( "Structure" ),
    this.projectService.getCodesByType( "Line" ),
    (structures, lines) => structures.concat(lines),
  )
  .subscribe(response => {
    this.structuresAndLines = response;
  });

}

---

使用Observable.forkjoin您可以在NGO上使用一个管道来传递两个数组。我也会尝试一下，从长远来看，这似乎更适合我。谢谢

handleProjectLoaded(project){

  Observable.zip(
    this.projectService.getCodesByType( "Structure" ),
    this.projectService.getCodesByType( "Line" ),
    (structures, lines) => structures.concat(lines),
  )
  .subscribe(response => {
    this.structuresAndLines = response;
  });

}