Label widgets are getting overwritten, how to delete

Question

I am making a unit converter, in which the user can freely choose the units he wants and convert them.

I was making the converter for temperature units(Celsius, Kelvin and Fahrenheit), and I stumbled across an error in which the Label widgets are getting overwritten even though I'm trying to delete them.

Heres the function which deals with this:

# Phase 2
def phase_2():

    # The Subphases
    # Temp
    def temprature():

        mega.forget()

        heading = Label(root, text="Temprature", padx=40, pady=15, relief=SUNKEN)
        heading.pack()

        frameps = LabelFrame(root)
        frameps.pack(padx=10, pady=10)

        def conversion():

            # Answer Box
            answer = LabelFrame(frameps, padx=10)
            answer.grid(row=3, column=4, columnspan=1, padx=20, pady=20)

            empty = Label(answer, text="Value")
            empty.grid(row=0, column=0)

            # C functions
            def C_F():                 
                empty = Label(answer, text=f"{(int(val.get()) * (9 / 5)) + 32}°F")
                empty.grid(row=0, column=0)

            def C_K():
                empty = Label(answer, text=f"{int(val.get()) + 273.15}°K")
                empty.grid(row=0, column=0)

            def C_C():
                empty = Label(answer, text=f"{int(val.get())}°C")
                empty.grid(row=0, column=0)

            # F functions
            def F_C():
                empty = Label(answer, text=f"{(int(val.get()) - 32) * 5/9}°C")
                empty.grid(row=0, column=0)

            def F_K():
                empty = Label(answer, text=f"{(int(val.get()) - 32) * 5/9 + 273.15}°K")
                empty.grid(row=0, column=0)

            def F_F():
                empty = Label(answer, text=f"{int(val.get())}°F")
                empty.grid(row=0, column=0)

            # K functions
            def K_F():
                empty = Label(answer, text=f"{(int(val.get()) - 273.15) * 9/5 + 32}°F")
                empty.grid(row=0, column=0)

            def K_C():
                empty = Label(answer, text=f"{int(val.get()) - 273.15}°C")
                empty.grid(row=0, column=0)

            def K_K():
                empty = Label(answer, text=f"{int(val.get())}°K")
                empty.grid(row=0, column=0)


            # C probs
            if unit.get() == "C" and u.get() == "F":
                answer.forget()
                C_F()
            if unit.get() == "C" and u.get() == "K":
                answer.forget()
                C_K()
            if unit.get() == "C" and u.get() == "C":
                answer.forget()
                C_C()
            
            # F probs
            if unit.get() == "F" and u.get() == "C":
                answer.forget()
                F_C()
            if unit.get() == "F" and u.get() == "K":
                answer.forget()
                F_K()
            if unit.get() == "F" and u.get() == "F":
                answer.forget()
                F_F()
            
            # K probs
            if unit.get() == "K" and u.get() == "F":
                answer.forget()
                K_F()
            if unit.get() == "K" and u.get() == "C":
                answer.forget()
                K_C()
            if unit.get() == "K" and u.get() == "K":
                answer.forget()
                K_K()

as you can see, i keep trying 'answer.forget' so that the label is forgotten, and then rewritten every time that i use the converter button, but instead, this happens:

You can change the text of a `Label` instead of recreating it every time https://stackoverflow.com/questions/17125842/changing-the-text-on-a-label — Pietro, Mar 29 '21 at 08:25

score 1 · Answer 1 · answered Mar 29 '21 at 09:06

The general idea is to build the layout once and change the values as needed, something like this:

import tkinter as tk


class MainApplication(tk.Frame):
    def __init__(self, parent, *args, **kwargs):
        tk.Frame.__init__(self, parent, *args, **kwargs)
        self.parent = parent

        self.count = 0

        self.label = tk.Label(self, text="Click the button!")
        self.label.pack()

        self.some_button = tk.Button(self, text="Click", command=self.some)
        self.some_button.pack()

        self.close_button = tk.Button(self, text="Close", command=self.quit)
        self.close_button.pack()

    def some(self):
        self.count += 1
        self.label["text"] = f"You clicked {self.count} times."


if __name__ == "__main__":
    root = tk.Tk()
    MainApplication(root).pack(side="top", fill="both", expand=True)
    root.mainloop()

So when you click the Convert button, you should call a function in your app, and inside that you read the values and setting that you need, and update the text inside the labels with the new results.

This answer explains how to structure your app with an OOP approach, that I think is very useful as your app grows.

Cheers!

score 0 · Answer 2 · answered May 30 '23 at 19:06

Labels are getting overwritten, how to delete

You had too many duplicate Label widgets for every function. So, using .configure will prevent overwritten.

The problem can be fixed.

    # C functions
    def C_F():                 
        empty.configure(text=f"{(int(val.get()) * (9 / 5)) + 32}°F")
        
    def C_K():
        empty.configure(text=f"{int(val.get()) + 273.15}°K")
        
    def C_C():
        empty.configure(text=f"{int(val.get())}°C")
         
    # F functions
    def F_C():
        empty.configure(text=f"{(int(val.get()) - 32) * 5/9}°C")
        
    def F_K():
        empty.configure(text=f"{(int(val.get()) - 32) * 5/9 + 273.15}°K")
        
    def F_F():
        empty.configure(text=f"{int(val.get())}°F")
        
    # K functions
    def K_F():
        empty.configure(text=f"{(int(val.get()) - 273.15) * 9/5 + 32}°F")
        
    def K_C():
        empty.configure(text=f"{int(val.get()) - 273.15}°C")
        
    def K_K():
        empty.configure(text=f"{int(val.get())}°K")

Label widgets are getting overwritten, how to delete

2 Answers2