Knockout extender to group the results of an observable array.

grouped-viewmodel.js

var ViewModel = function( data ) {
	this.observableArrayObject = ko.observableArray( data.items ).extend( { 'grouped': 4 } );
};

grouped.knockout.js

/**
 * Extends an observable array to return grouped results
 * @param  {observable}		target		Obvervable property being extended
 * @param  {int}			numColumns	Number of items to be in each group
 * @return {observable}					Resulting grouped array
 */
ko.extenders.grouped = function( target, numColumns ) {
	var arrValues = target(),
		columns = ( numColumns || 2 );
	target.groupedItems = ko.computed( function() {
			var rows = [],
				current = [],
				i = 0,
				max = arrValues.length;
			rows.push(current);
			for ( i; i < max; i += 1) {
				current.push(arrValues[i]);
				if (((i + 1) % columns) === 0) {
					current = [];
					rows.push(current);
				}
			}
			return rows;
		}, this);

	return target;
};

sample-usage.html

<div id="sampleApp">
	<div data-bind="foreach: observableArrayObject.groupedItems()">
		<div data-bind="foreach: $data" class="row">
			<div class="col-sm-6">
				<div class="checkbox">
					<label data-bind="text: label"></label>
				</div>
			</div>
		</div>
	</div>
</div>