How to access a variable outside of a function (access from a loop)?

Question

I am working on accessing a variable outside of a function. Here is part of my code:

def main():
    trigger_gmm() = 0
    log = []
    def spatter_tracking_cb(ts, clusters):
        global trigger_gmm
        for cluster in clusters:
            log.append([ts, cluster['id'], int(cluster['x']), int(cluster['y']), int(cluster['width']),
                        int(cluster['height'])])
             if cluster['width'] >= 200:
                 trigger_gmm = 1
             else:
                 trigger_gmm = 0
             print(trigger_gmm)
while True:
    print(trigger_gmm)
    if trigger_gmm == 1:
        print("print something")

if __name__ == "__main__":
    main()

I get the output like this:

NameError: name 'trigger_gmm' is not defined

Any ideas would be much appreciated!

Answer 1

You have three issues in that code:

1. trigger_gmm() = 0 - You need to remove the parenthesis
2. You need to move the global variable definition up to the beginning of the main function
3. The if __name__ == "__main__": is not reached as it is after the while loop, you need to move it up.

EDIT: I added a global declaration to the main module (above the main function) and inside the spatter_tracking_cb function. This is because you need to indicate that the variable trigger_gmm is a global variable whenever you use it.

This code seems to work for me:

global trigger_gmm


def main():
    global trigger_gmm
    trigger_gmm = 0
    log = []

    def spatter_tracking_cb(ts, clusters):
        global trigger_gmm
        for cluster in clusters:
            log.append([ts, cluster['id'], int(cluster['x']), int(cluster['y']), int(cluster['width']),
                        int(cluster['height'])])
            if cluster['width'] >= 200:
                trigger_gmm = 1
            else:
                trigger_gmm = 0
            print(trigger_gmm)


if __name__ == "__main__":
    main()

while True:
    print(trigger_gmm)
    if trigger_gmm == 1:
        print("print something")