passing dynamic data from a while loop to other modules

April 6, 2023

I have a function below that should be constantly running every second, making api calls and receiving data. Api_data is an instance of a class defined separately. I am building a list with 5 most recent data points. I want to be able to use my_DataPoints in other functions and modules, for example to build a json with the received recent data and I am not sure how to pass and access its value. I defined global variables but I am not sure if this is the correct way and how to import them. I would appreciate your help

def get_data(api_data):
    interval= 5
    global my_DataPoints
    global myData
    my_DataPoints= []
    myData = {}
        
    while True:
        for x in range(interval):
            start= time.time()
            myData= api_data
            print(myData.rTime)
            my_DataPoints.append(myData)
                    
            if (len(my_DataPoints)-1) ==interval:
                my_DataPoints.pop(0)
            print(my_DataPoints)  
                
                
            end= time.time()
            if (end -start) < 1:
                time.sleep(1-(end-start))

>Solution :

Instead of using global variables, you can define your get_data function to return the my_DataPoints list after it’s done collecting the data. Then, you can assign the returned list to a variable in your main script, which you can then pass to other functions.

Here’s an example of how you can modify your get_data function to return the my_DataPoints list:

def get_data(api_data):
    interval= 5
    my_DataPoints= []
    myData = {}
        
    while True:
        for x in range(interval):
            start= time.time()
            myData= api_data
            print(myData.rTime)
            my_DataPoints.append(myData)
                    
            if (len(my_DataPoints)-1) ==interval:
                my_DataPoints.pop(0)
            print(my_DataPoints)  
                
                
            end= time.time()
            if (end -start) < 1:
                time.sleep(1-(end-start))
                
        yield my_DataPoints

In your main script, you can then call the function and assign the returned list to a variable like this:

api_data = ApiData()  # assuming ApiData is the class for your API data
data_points = get_data(api_data)  # get the generator object

while True:
    my_DataPoints = next(data_points)  # get the next set of data points
    # do something with my_DataPoints, e.g. build a JSON object
    time.sleep(1)  # wait for 1 second before getting the next set of data points

Note that get_data now returns a generator object that yields the my_DataPoints list every interval seconds. The next function is used to retrieve the next set of data points. You can then use the my_DataPoints list as needed in your main script.