enable/disable group of elements on input[radio] selected for angular 2 with reactive forms (ReactiveFormsModule)

my-form.ts

//angular 2 (TypeScript, ReactiveFormsModule)
export class MyForm {
  form: FormGroup;

  constructor(fb: FormBuilder) {
    this.form = fb.group({
      radioInput: '',
      group1: fb.group({
        ctr0: '',
        ctr1: '',
        //...etc
      }),
    });
  }

  ngAfterViewInit() {
    this.form.valueChanges
      .subscribe(value => this.enableControl(
        'group1',
        value.radioInput === 'group1'
      ));
  }

  enableControl(name, value) {
    const el = this.form.get(name);
    if (!el || el.enabled === value) {
      return;
    }
    if (value) {
      el.enable();
    } else {
      el.disable();
    }
  }
}