port_cleaner.sh

#! /bin/bash

# exit on error
set -e

the_list=($( port installed | grep -v active | grep -v : ))

size=${#the_list[@]}
let size=$size-1
echo $size
for ((i=0; i < size; i+=2))
do
	sudo port uninstall ${the_list[i]} ${the_list[i+1]}
done

Sometimes it has to be executed several times (removing set -e), since it is not smart enough to uninstall dependant before the dependencies)). Or mannually delete the dependents and restart the script.