How to use Python to retrieve the Average Value in a Tkinter Treeview Column?

 

from tkinter import *
from tkinter import ttk
from dbms.billing_backend import billing_history12

class Hancie():
    def __init__(self, main):
        self.main=main
        self.main.title("Hancie e-Learning Studio")
        self.main.resizable(0, 0)
        frame_width = 1050
        frame_height = 500
        screen_width = self.main.winfo_screenwidth()
        screen_height = self.main.winfo_screenheight()
        x_cordinate = int((screen_width / 2) - (frame_width / 2))
        y_cordinate = int((screen_height / 2) - (frame_height / 2))
        self.main.geometry('{}x{}+{}+{}'.format(frame_width, frame_height, x_cordinate+50, y_cordinate+50))

        treeView=ttk.Treeview(self.main)
        treeView.pack(side=BOTTOM, fill=BOTH, expand=True)
        treeView['columns']=('bookingid', 'name','km','unit','total')
        treeView.column('#0', width=0, stretch=0)
        treeView.column('bookingid', width=100, anchor=CENTER)
        treeView.column('name', width=200, anchor=CENTER)
        treeView.column('km', width=100, anchor=CENTER)
        treeView.column('unit', width=100, anchor=CENTER)
        treeView.column('total', width=150, anchor=CENTER)

        treeView.heading('#0', text='', anchor=CENTER)
        treeView.heading('bookingid',text='ID', anchor=CENTER)
        treeView.heading('name', text='Name', anchor=CENTER)
        treeView.heading('km', text='KM', anchor=CENTER)
        treeView.heading('unit', text='Unit', anchor=CENTER)
        treeView.heading('total', text='Total', anchor=CENTER)



        def billingtable():

            historyResult=billing_history12()

            for ro in historyResult:
                treeView.insert(parent='', index='end', values=(ro[0],ro[1],ro[6],ro[7],ro[8]))


        billingtable()

        def getaverage(item=""):
            val = 0
            for row in treeView.get_children(item):
                # print(trv.item(row)["values"][3])# print price
                val = val + treeView.item(row)["values"][4]
                average = val / len(treeView.get_children())

            treeView.insert(parent='', index='end', values=('','','','',"Average: {}".format(average)))

        getaverage()



if __name__=='__main__':
    main=Tk()
    Hancie(main)
    main.mainloop()

Output