execfile or os.system

execute the other python file in place:

execfile("/path/to/my/lib/mylib.py")

or:

import os
os.system("python /path/to/my/lib/mylib.py")

import

import sys 
import os
sys.path.append(os.path.abspath("/path/to/my/lib"))
import mylib

ref

See other methods here.