import python file from previous folder code example

Example 1: python import file from parent directory

import os,sys,inspect
currentdir = os.path.dirname(os.path.abspath(inspect.getfile(inspect.currentframe())))
parentdir = os.path.dirname(currentdir)
sys.path.insert(0,parentdir) 

import mymodule

OR 

import os, sys

sys.path.insert(1, os.getcwd()) 
import variables

Example 2: how to determine python project parent dir

import os,sys,inspect
currentdir = os.path.dirname(os.path.abspath(inspect.getfile(inspect.currentframe())))
parentdir = os.path.dirname(currentdir)
sys.path.insert(0,parentdir) 

import mymodule

OR 

import os, sys

sys.path.insert(1, os.getcwd()) 
import variables