title: Add class to HTML select depending on Radio button value in Angular JS
body: <p>I have 3 radio button. Depending upon the radio button selected, I want to make the dropdownlist single select and multiple select and disabled. Any Help? What is the scope of using ng-class for this?</p>
  
  <p>On page load, Multiple RadioButton will be checked and the DDL will be Multi-select.)
  If I change, radiobuttonValue == single, then DDL should be normal one(remove multi-select
  and if radiobuttonValue == all, then DDL should be disabled</p>
  
  <pre><code>&lt;div class="form-group"&gt;
                      &lt;div class="col-sm-4"&gt;
                          &lt;div class="radio"&gt;
                              &lt;label&gt;
                                  &lt;input type="radio" name="portRadios" id="portRadios1" value="single" ng-model="activity.portRadios"&gt;
                                  Single Port
                              &lt;/label&gt;
                              &lt;label&gt;
                                  &lt;input type="radio" name="portRadios" id="portRadios2" value="multiple" ng-model="activity.portRadios" checked="checked"&gt;
                                  Multiple Port
                              &lt;/label&gt;
                              &lt;label&gt;
                                  &lt;input type="radio" name="portRadios" id="portRadios3" value="all" ng-model="activity.portRadios"&gt;
                                  All Ports
                              &lt;/label&gt;
                          &lt;/div&gt;
                      &lt;/div&gt;
                  &lt;/div&gt;
                  &lt;div class="form-group"&gt;
                      &lt;label class="col-sm-2 control-label"&gt;City/Port :&lt;/label&gt;
                      &lt;div class="col-sm-4"&gt;
                          &lt;select multiple name="ActivityPort" class="form-control" ng-model="activity.selectedPort" ng-show="portradios == single" ng-options="b.Name for b in portList track by Name"&gt;
                              &lt;option value=""&gt;-- Select a Port --&lt;/option&gt;
                          &lt;/select&gt;
                      &lt;/div&gt;
                  &lt;/div&gt;
  </code></pre>