Magento: Adding New option Most viewed or most popular option in sort by drop down in category list page in Magento

If you need to added a new sort by option like most viewed or most popular in drop down option then follow these steps–

override app\code\core\Mage\Catalog\Block\Product\List\Toolbar.php

in local folder and add or override only this 2 functions
Replace default Toolbar.php code by this code (be care full on class name it depends on your module name)

I took ex;- Most Viewed

<?php

class Yourmodule_Catalog_Block_Product_List_Toolbar extends Mage_Catalog_Block_Product_List_Toolbar
{

/**
* Retrieve available Order fields list
*
* @return array
*/
public function getAvailableOrders()
{


$this->addOrderToAvailableOrders('mostviewd', 'Most Popular');

$this->removeOrderFromAvailableOrders('position');
$this->removeOrderFromAvailableOrders('relevance');
$this->setDefaultOrder('mostviewd');
$this->setDefaultDirection('asc');
$this->removeOrderFromAvailableOrders('entity_id');
krsort($this->_availableOrder);
return $this->_availableOrder;
}


public function setCollection($collection)
{
$this->_collection = $collection;

$this->_collection->setCurPage($this->getCurrentPage());

// we need to set pagination only if passed value integer and more that 0
$limit = (int)$this->getLimit();
if ($limit) {
$this->_collection->setPageSize($limit);
}
if ($this->getCurrentOrder()) {
$this->_collection->setOrder($this->getCurrentOrder(), $this->getCurrentDirection());
}
if($this->getCurrentOrder()=='mostviewd') {
$this->_collection->getSelect()->
joinInner('report_event AS _table_views',
' _table_views.object_id = e.entity_id',
'COUNT(_table_views.event_id) AS views')->
group('e.entity_id')->order('views DESC');
}

$sql = $this->_collection->getSelectSql(true);

$this->_collection->getSelect()->reset()->from(
array('e' =>new Zend_Db_Expr("({$sql})")),
array('e' => "*")
);
$limit= $this->getDefaultPerPageValue();
$page = $this->getRequest()->getParam('p');

if(isset($page))
if(($page - 1) == 0)
$this->_collection->getSelect()->limit($limit);
else
$this->_collection->getSelect()->limit($limit, ($page - 1) * $limit);
else
$this->_collection->getSelect()->limit($limit);

$this->_collection->load();


// $this->_collection->printlogquery(true); exit;
return $this;
}


}