Magento - Get list of all Manufacturers with product count - magento-1.7

Question

I am using the following code to list all the manufacturers and it works like a charm:
$attribute = Mage::getModel('eav/entity_attribute')
->loadByCode('catalog_product', 'manufacturer');
$valuesCollection = Mage::getResourceModel('eav/entity_attribute_option_collection')
->setAttributeFilter($attribute->getData('attribute_id'))
->setStoreFilter(0, false);
$preparedManufacturers = array();
foreach($valuesCollection as $value) {
$preparedManufacturers[$value->getOptionId()] = $value->getValue();
}
if (count($preparedManufacturers)) {
echo "<h2>Manufacturers</h2><ul>";
foreach($preparedManufacturers as $optionId => $value) {
echo "<li>" . $value . " - (" . $optionId . ")</li>";
}
echo "</ul>";
}
What I am looking for is a way to display the number of products associated with each of the manufacturers. Can someone please tell me the way of doing this?
Many thanks

Answer 1

Not all mine, but works for me in 1.6+?
<?php
include_once 'app/Mage.php';
Mage::app();
$attribute = Mage::getModel('eav/entity_attribute')
->loadByCode('catalog_product', 'manufacturer');
$valuesCollection = Mage::getResourceModel('eav/entity_attribute_option_collection')
->setAttributeFilter($attribute->getData('attribute_id'))
->setStoreFilter(0, false);
$preparedManufacturers = array();
foreach ($valuesCollection as $value) {
$preparedManufacturers[$value->getOptionId()] = $value->getValue();
}
if (count($preparedManufacturers)) {
echo "<h2>Manufacturers</h2><ul>";
foreach ($preparedManufacturers as $optionId => $value) {
$collection = Mage::getModel('catalog/product')->getCollection();
$collection->addFieldToFilter(array(array('attribute' => 'manufacturer', 'eq' => $optionId)));
$mumberOfProducrt = count($collection);
echo "<li>" . $value . " - (" . $mumberOfProducrt . ")</li>";
}
echo "</ul>";
}
?>

Answer 2

This would work but won't be the most efficient:
foreach($valuesCollection as $value) {
$preparedManufacturers[$value->getOptionId()] = $value->getValue();
$collection = Mage::getModel('catalog/product')->getCollection();
$collection
->addAttributeToSelect('*') // '*' not efficient though
->addAttributeToFilter('manufacturer', array('eq' => $value->getOptionId()))
//->addAttributeToFilter('manufacturer', $value->getOptionId())
;
$count = $collection->->getSize();
}
It's an extra query for each manufacturer so it's not great, if you have some caching etc it won't be too bad though.

Answer 3

Working code should do it
$collection = Mage::getModel('catalog/product')->getCollection()->groupByAttribute('manufacturer')
->addFieldToFilter('status',Mage_Catalog_Model_Product_Status::STATUS_ENABLED)
->addExpressionAttributeToSelect("count",'COUNT({{entity_id}})', 'entity_id');
Mage::getSingleton('cataloginventory/stock')->addInStockFilterToCollection($collection);