Scroll + limitTo

HTML

<h2>What I have</h2>

<div class="test" ng-controller="Ctrl">
    <div ng-repeat="division in divisions | orderBy:['!-sub','group']">{{division.group}}-{{division.sub}}</div>
</div>

<h2>What I want</h2>

<div>1-4</div>
<div>3-3</div>
<div>6-2</div>
<div>4-1</div>
<div>2-</div>
<div>5-</div>

CSS

.test {
    margin-bottom:20px;
}

JavaScript

var app = angular.module('app', []);

function Ctrl($scope) {
    $scope.divisions = [{
        'group': 1,
            'sub': 4
    }, {
        'group': 2,
            'sub': null
    }, {
        'group': 3,
            'sub': 3
    }, {
        'group': 4,
            'sub': 1
    }, {
        'group': 5,
            'sub': null
    }, {
        'group': 6,
            'sub': 2
    }];
}