How to return an array from my subscriber function

edit

I assume you want the latitude and longitude values from one message in your main thread?

You can wait on a result from the subscriber using a threading.Event object. The "InfoGetter" is better contained in a class than global variables and a function. Here is working code.

import rospy
from sensor_msgs.msg import NavSatFix
import threading


class InfoGetter(object):
    def __init__(self):
        #event that will block until the info is received
        self._event = threading.Event()
        #attribute for storing the rx'd message
        self._msg = None

    def __call__(self, msg):
        #Uses __call__ so the object itself acts as the callback
        #save the data, trigger the event
        self._msg = msg
        self._event.set()

    def get_msg(self, timeout=None):
        """Blocks until the data is rx'd with optional timeout
        Returns the received message
        """
        self._event.wait(timeout)
        return self._msg

if __name__ == '__main__':
    rospy.init_node('infoGetter', anonymous=True)
    #Get the info
    ig = InfoGetter()
    rospy.Subscriber("/novatel/fix", NavSatFix, ig)
    #ig.get_msg() Blocks until message is received
    msg = ig.get_msg()
    print msg

You can test that this code works by starting a roscore, running this script, and executing the following command

rostopic pub /novatel/fix sensor_msgs/NavSatFix "{latitude: 4.0, longitude: 5.0}"