AngularJS (ng-grid) order by original index -

when grid rendered, follows ordering of list (model) behind it. how 1 revert same natural ordering after sort column has occurred?

within ng-repeater set custom data attribute {{$index}}

<li class="sortable" ng-repeat="item in items" data-index="{{$index}}"> 

then when dom manipulated produce column sort index when rendered preserved within data-index