Topic not subscribed to properly [closed]

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I only need to manipulate the data... but I need to save a local copy? I ask because I don't remember seeing that in the tutorial. That print statement is for debugging.

The message data is passed into the callback as an argument; it isn't valid outside the callback unless you assign it into a global variable.

Alternately, you can do all of your processing inside the callback routine.

Ok. Thank you. I'll see what I can come up with.

Ok. I've done this... but am receiving the error:

NameError: global name 'ilimb_pos' is not defined

... except that's what I thought I was doing in the callback(data) function But, if I uncomment the variable definition in "ilimb_pos none"... then I receive "none" as the output of the print command

Program_Name = "./handcontrol"
#ilimb_pos = None

def callback(data):
    rospy.loginfo(rospy.get_caller_id()+"I heard %s",data.data)
    global ilimb_pos
    ilimb_pos = data

def ilimb_grip_pub():

    # this listens to a user input for a user-defined hand configuration
    rospy.init_node('ilimb_grip_pub', anonymous=True)
    rospy.Subscriber("ilimb_define_pos", String, callback)     

    #this creates the publisher topic
    #rospy.init_node('ilimb_move', anonymous=True)
    r = rospy.Rate(10) # 10hz


    while not rospy.is_shutdown():
        #print Callback_Data
        print ilimb_pos

I would expect it to work if you uncomment the variable definition in the top-level scope. That said, I would expect it to print None until it receives the first message.

that does "fix" the issue... but that brings up another problem. I'm wanting to manipulate the subscribed data and expect it, "data" to be of type "string".... (should I start a new thread?) Here's the code I'm currently looking at:

ilimb_pos = None
l1 = []

def callback(data):
    rospy.loginfo(rospy.get_caller_id()+"I heard %s",data.data)
    global ilimb_pos
    ilimb_pos = data
    print ilimb_pos

    for elem in ilimb_pos:
        l1.extend(elem.strip().split(" "))
    print l1

I get this error:

for elem in ilimb_pos:
TypeError: 'String' object is not iterable

I'm researching now but could use a point in the right direction.

Please review the rospy tutorial and the definition for a string message again. The object your callback is receiving is a std_msgs/String object, which contains a single member called data which is a string. You log statement gets this right.