title: Select default selected value in select tag in Angular 5
body: <p>here is my code</p>
  
  <pre><code>&lt;select class="form-control input-transparent" id="select-field" name="address" ngModel required&gt;
       &lt;optgroup *ngFor="let wallet of wallets" label="{{wallet.label}}"&gt;
           &lt;option value="{{ wallet.address }}" [selected]="wallet.address == wallets[0].address"&gt;{{ wallet.address }}&lt;/option&gt;
       &lt;/optgroup&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>I want to select first option as selected but still on default value was selected</p>