php - how to parse an xml and show only the row where there is a particular value?

I have an xml which is similar to this:

<xml>
<products name="product_list">
<product id="1" name="product_1">Soap</product>
<product id="2" name="product 3">Shampoo</product>
<product id="3" name="product_3">Sponge</product>
</products>
</xml>

I'm trying to import it via php (using simplexml) but I would like show only one row where the id match another variable I've set.

Something like :

echo product where product['id'] = $variable 

But I have no idea how to do that.