title: Angular 5 reactive form - disable one radio option in radio group
body: <p>I have a radio group which uses the same form control for each option. Is it possible to disable just the red radio button? I know you can set the disabled flag on the <strong>color</strong>  form control but this will disabled all radio buttons. </p>
  
  <pre><code>&lt;fieldset [formGroup]="colorForm"&gt;
      &lt;legend&gt;
        Choose color
      &lt;/legend&gt;
  
  &lt;div class="radio"&gt;
    &lt;label&gt;
      &lt;input type="radio" value="red" formControlName="color"&gt;
      Red
    &lt;/label&gt;
  &lt;/div&gt;
  
  &lt;div class="radio"&gt;
    &lt;label&gt;
      &lt;input type="radio" value="green" formControlName="color"&gt;
      Green
    &lt;/label&gt;
  &lt;/div&gt;
  
  &lt;div class="radio"&gt;
    &lt;label&gt;
      &lt;input type="radio" value="blue" formControlName="color"&gt;
      Blue
    &lt;/label&gt;
  &lt;/div&gt;
  </code></pre>