Magento 2 : Rating Filter in Layered Navigation

create one file Called Rating.php as of now i did in core module only which can be implemented in your custom module vendor\magento\module-catalog\Model\Layer\Filter\Rating.php

<?php
/**
 * Copyright © 2015 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */

namespace Magento\Catalog\Model\Layer\Filter;


use Magento\Catalog\Model\Category as CategoryModel;
use Magento\Catalog\Model\CategoryFactory as CategoryModelFactory;
use Magento\Catalog\Model\Layer;
use Magento\Framework\Registry;
/**
 * Layer category filter
 *
 * @author      Magento Core Team <[email protected]>
 */
class Rating extends \Magento\Catalog\Model\Layer\Filter\AbstractFilter
{
    /**
     * Active Category Id
     *
     * @var int
     */
    protected $_categoryId;

    /**
     * Applied Category
     *
     * @var \Magento\Catalog\Model\Category
     */
    protected $_appliedCategory;

    /**
     * Core data
     *
     * @var \Magento\Framework\Escaper
     */
    protected $_escaper;

    /**
     * Core registry
     *
     * @var \Magento\Framework\Registry
     */
    protected $_coreRegistry;

    /**
     * @var CategoryDataProvider
     */
    private $dataProvider;

    /**
     * Construct
     *
     * @param \Magento\Catalog\Model\Layer\Filter\ItemFactory $filterItemFactory
     * @param \Magento\Store\Model\StoreManagerInterface $storeManager
     * @param \Magento\Catalog\Model\Layer $layer
     * @param \Magento\Catalog\Model\Layer\Filter\Item\DataBuilder $itemDataBuilder
     * @param \Magento\Framework\Escaper $escaper
     * @param CategoryFactory $categoryDataProviderFactory
     * @param array $data
     */
    public function __construct(
        \Magento\Catalog\Model\Layer\Filter\ItemFactory $filterItemFactory,
        \Magento\Store\Model\StoreManagerInterface $storeManager,
        \Magento\Catalog\Model\Layer $layer,
        \Magento\Catalog\Model\Layer\Filter\Item\DataBuilder $itemDataBuilder,
        \Magento\Framework\Escaper $escaper,
        array $data = []
    ) {
        parent::__construct($filterItemFactory, $storeManager, $layer, $itemDataBuilder, $data);
        $this->_escaper = $escaper;
        $this->_requestVar = 'rat';
    }


    /**
     * Get filter value for reset current filter state
     *
     * @return mixed|null
     */
    public function getResetValue()
    {
        return $this->dataProvider->getResetValue();
    }

    /**
     * Apply category filter to layer
     *
     * @param   \Magento\Framework\App\RequestInterface $request
     * @return  $this
     */
    public function apply(\Magento\Framework\App\RequestInterface $request)
    {
        /**
         * Filter must be string: $fromPrice-$toPrice
         */
        $filter = $request->getParam($this->getRequestVar());
        if (!$filter) {
            return $this;
        }
        $filter = explode('-', $filter);
        list($from, $to) = $filter;
         $collection = $this->getLayer()->getProductCollection();

        $collection->getSelect()->joinLeft(array('rova'=> 'rating_option_vote_aggregated'),'e.entity_id =rova.entity_pk_value',array("percent"))
        ->where("rova.percent between ".$from." and ".$to)
        ->group('e.entity_id'); 
        //$this->getLayer()->getState()->addFilter($this->_createItem($text, $filter));
        //$collection->printlogquery(true);
        return $this;
    }

    /**
     * Get filter name
     *
     * @return \Magento\Framework\Phrase
     */
    public function getName()
    {
        return __('Rating');
    }





       /**
     * Get data array for building attribute filter items
     *
     * @throws \Magento\Framework\Exception\LocalizedException
     * @return array
     */
    protected function _getItemsData()
    {

        $facets = array(
            '0-20'=>'1 Start',
            '21-40'=>'2 Start',
            '41-60'=>'3 Start',
            '61-80'=>'4 Start',
            '81-100'=>'5 Start'
            );
     $collection = $this->getLayer()->getProductCollection();
        $data = [];
        if (count($facets) > 1) { // two range minimum
            $i=1;
            foreach ($facets as $key => $label) {
               $count=$this->prepareData($key,$collection,$i);
               $i++;
               $this->itemDataBuilder->addItemData(
                    $this->_escaper->escapeHtml($label),
                    $key,
                    $count
                );
            }
        }

        return $this->itemDataBuilder->build();

        /* $this->itemDataBuilder->addItemData(
            $this->tagFilter->filter('5 star'),
            '80-100',
            1
        );
        return $this->itemDataBuilder->build(); */
    }
    /**
     * @param string $key
     * @param int $count
     * @return array
     */
    private function prepareData($filter,$collection,$i)
    {
       $filter = explode('-', $filter);
        list($from, $to) = $filter;
          /** @var \Magento\CatalogSearch\Model\ResourceModel\Fulltext\Collection $productCollection */


        $collection->getSelect()->joinLeft(array('rova'.$i=> 'rating_option_vote_aggregated'),'e.entity_id =rova'.$i.'.entity_pk_value',array("percent"))
        ->where("rova".$i.".percent between ".$from." and ".$to)
        ->group('e.entity_id'); 
        //$collection->printlogquery(true); echo '<br>............................<br>';
        return $collection->getSize();
    }
}

and in vendor\magento\module-catalog\Model\Layer\FilterList.php add rating filter option if you wrote custom module add this option by plugin

public function getFilters(\Magento\Catalog\Model\Layer $layer)
    {
        if (!count($this->filters)) {
            $this->filters = [
                $this->objectManager->create($this->filterTypes[self::CATEGORY_FILTER], ['layer' => $layer]),
                 $this->objectManager->create($this->filterTypes['Magento\Catalog\Model\Layer\Filter\Rating'], ['layer' => $layer]),
            ];
            foreach ($this->filterableAttributes->getList() as $attribute) {
                $this->filters[] = $this->createAttributeFilter($attribute, $layer);
            }
        }
        return $this->filters;
    }

it will bring rating filter and do filter with product collection but still product count and adding to state i not done if some one did please pot it