the package org.apache.mahout.cf.taste.hadoop.item is more misleading.
mahout has two type recommendation model,
User based and item based, org.apache.mahout.cf.taste.hadoop.item mislead people to consider that org.apache.mahout.cf.taste.hadoop.item is item based.
but truth is that :
if the input format 's user_id,item_id,score ,then recommend user with similar items,
if the input format 's item_id,user_id,score ,then recommend item with similar user,it can be used for advertisement pushing.
so the best way is to change package name.