name error global name 'x' is not defined...help

[Johnny James]

import subprocess
import sys
import time
import os

def main():
	#Check to see if quickdraw is located in the correct palce
	quickfile = file_existance()
	quickdraw = subprocess.Popen(['java', '-jar', quickfile], stdin = subprocess.PIPE)
	#Intro, explaining what will occur throughout program
	intro()
	#
	x_coordinate(1)
	y_coordinate(1)
	initial_ball(quickdraw)


def file_existance():
        filename = raw_input("Please enter the name of the file: ")
        while (not os.path.isfile(filename)):
                print "That file does not exist, try again"
                filename = raw_input("Please enter the name of the file: ")
        print os.path.abspath(filename)
        return filename

def intro():
	print "For this assignment you will be asked to give coordinates for a ball,"
	print "after you have given the coordinates, the ball will continually bounce"
	print "until it runs out of energy and comes to a complete stop."

def x_coordinate(num):
	num= num+1
	x= int(input("Please enter the x-coordinate (between 0 and 600) where you would like the ball placed: "))
	if (x <= 600) and (x >= 0):
		print "Valid choice"
		return x
	else:
		print "invalid choice, choose again please"
		if num > 3:
			x = 300
			return x
		else:
			x_coordinate(num)
	return x

def y_coordinate(num):
	num= num+1
	y= int(input("Please enter the y-coordinate (between 0 and 600) where you would like the ball placed: "))
	if (y >= 0) and (y <= 600):
		print "Valid choice"
		return y
	else:
		print "invalid choice, choose again please"
		if num > 3:
			y = 300
			return y
		else:
			y_coordinate(num)	
	


def initial_ball(quickdraw):
	radius= 300
	ball = "fillcircle" + ' ' + str(x) + ' ' + str(y) + ' ' + str(radius)
	quickdraw.stdin.write(ball)
	quickdraw.stdin.write("\n")

The error is that the global name 'x' is not defined. But I dont understand why because I returned the variable...

[bvdet]

You should assign x_coordinate(1) to an identifier and pass that as an additional parameter to initial_ball(). You must do the same for y_coordinate(1).

You could also do this:

    initial_ball(quickdraw,
                 x_coordinate(1),
                 y_coordinate(1))

Redefine initial_ball: def initial_ball(qu ickdraw, x, y):