How can i make one function repeat by pressing button several times in Python tkinter?

Question

from tkinter import *

root = Tk()

numL = 0
numD = 0

root.geometry("200x100")

def like():
    root_label1.config(text=numL+1)

def dlike():
    root_label2.config(text=numD+1)

root_button1 = Button(root, text="Like", command=like)
root_button2 = Button(root, text="Dislike", command=dlike)

root_label1 = Label(root, text=numL)
root_label2 = Label(root, text=numD)

root_button1.grid(row=0,column=0)
root_button2.grid(row=0,column=1)

root_label1.grid(row=1,column=0)
root_label2.grid(row=1,column=1)

root.mainloop()

This code is working without errors but when I press like or dislike button the labels change from 0 to 1 only one time then nothing happens however what I want is when ever I press any button the numbers keep on adding themselves with one.

You did not update `numL` and `numD` inside the two functions. — acw1668, Jun 25 '21 at 11:25

score 3 · Accepted Answer · 2021-06-25T11:40:57.043

3

def like():
    global numL
    numL+=1
    root_label1.config(text=numL)
    

def dlike():
    global numD
    numD+=1
    root_label2.config(text=numD)

You need to update the numL and numD. Your function fetches the value of numL and numD as 0 because you never update it.

edited Jun 25 '21 at 11:40

answered Jun 25 '21 at 11:29

It should be `numL` – PCM Jun 25 '21 at 11:32
I changed it to `numL` still doesn't work – PCM Jun 25 '21 at 11:32
Shows: local variable 'numL' referenced before assignment – PCM Jun 25 '21 at 11:33
So you need to use global keyword or pass it as a argument – PCM Jun 25 '21 at 11:33
1

@PCM Make all the comments onto a single one, instead of spamming. – Delrius Euphoria Jun 25 '21 at 11:34
Better to move `num+=1` above `config` so you can just `config(text=numL)`. – Delrius Euphoria Jun 25 '21 at 11:39

PCM · Answer 2 · 2021-06-25T11:30:12.717

Use Lists to make it easier. Also, len() and more functions can be used -

from tkinter import *

root = Tk()

numL = []
numD = []

root.geometry("200x100")

def like():
       numL.append(0)
       root_label1.config(text=len(numL))

def dlike():
    numD.append(0)
    root_label2.config(text=len(numD))

root_button1 = Button(root, text="Like", command=like)
root_button2 = Button(root, text="Dislike", command=dlike)

root_label1 = Label(root, text=len(numL))
root_label2 = Label(root, text=len(numD))

root_button1.grid(row=0,column=0)
root_button2.grid(row=0,column=1)

root_label1.grid(row=1,column=0)
root_label2.grid(row=1,column=1)

I used len(lists) for the text. This worked for me. And it should work for you

Why would you make `numL` and `numD` lists? Lists take up more memory than integers so there is no point. Also appending to a list takes more time than adding 1 to an integer. — TheLizzard, Jun 25 '21 at 12:24

Shamim Sanisales · Answer 3 · 2021-06-25T13:42:05.550

1

from tkinter import *

root = Tk()

global numL
numL = 0
numD = 0

root.geometry("200x100")

def like():
    numL = int(str(root_label1['text']))
    numL = numL+1
    root_label1.config(text=numL)

def dlike():
    numD = int(str(root_label2['text']))
    numD = numD + 1
    root_label2.config(text=numD)

root_button1 = Button(root, text="Like", command= like)
root_button2 = Button(root, text="Dislike", command=dlike)

root_label1 = Label(root, text=numL)
root_label2 = Label(root, text=numD)

root_button1.grid(row=0,column=0)
root_button2.grid(row=0,column=1)

root_label1.grid(row=1,column=0)
root_label2.grid(row=1,column=1)

root.mainloop()

You should save new values in variables

edited Jun 25 '21 at 13:42

answered Jun 25 '21 at 11:32

Shamim Sanisales

21
4

2

I think you missed `global`. – Delrius Euphoria Jun 25 '21 at 11:33
I just rewrite the functions. Global variables are in the main code. – Shamim Sanisales Jun 25 '21 at 11:35
@ShamimSanisales this will raise `UnboundLocalError` [read](https://stackoverflow.com/questions/423379/using-global-variables-in-a-function) – Art Jun 25 '21 at 11:42
Pass numL and numD as aa argument to your functions. I believe this can work. – Shamim Sanisales Jun 25 '21 at 11:45
1

@ShamimSanisales That isn't going to work because you are passing it by value not by reference. – TheLizzard Jun 25 '21 at 12:31
you are right, check it now. It's work for me. so I should work for you too :) – Shamim Sanisales Jun 25 '21 at 13:43
This solution is much slower than @ Sujay's solution. In your case you get a string object and then pass it through `str` then `int`, then you store it, add 1 to it, and then use it. – TheLizzard Jun 25 '21 at 16:32
I use this one because globalization is not a really safe solution. and also it's another way for solving this question. – Shamim Sanisales Jun 27 '21 at 05:27

score 1 · Answer 4 · answered Jun 26 '21 at 05:53

your code should be this :- from tkinter import *

root = Tk()
numLvar = 0
numL = StringVar()
numL.set(numLvar)
numDvar = 0
numD = StringVar()
numD.set(numDvar)

root.geometry("200x100")

def like():
    global numLvar
    # root_label1.config(text=numL+1)
    numLvar += 1
    numL.set(numLvar)
    root_label1.update()


def dlike():
    global numDvar
    # root_label1.config(text=numL+1)
    numDvar += 1
    numD.set(numDvar)
    root_label2.update()

root_button1 = Button(root, text="Like", command=like)
root_button2 = Button(root, text="Dislike", command=dlike)

root_label1 = Label(root, textvariable=numL)
root_label2 = Label(root, textvariable=numD)

root_button1.grid(row=0,column=0)
root_button2.grid(row=0,column=1)

root_label1.grid(row=1,column=0)
root_label2.grid(row=1,column=1)

root.mainloop()

Code explanation : whenever you want to change the text in a label... text = text will not work.... you need textvariable = varname for this purpose and it must be a supported vaiable type in tkinter... here i have used StringVar as its the most convinient one..... also after changing its value in function... you need to set the textvariable again using the .set() method.... and also use .update() for the label to update it to the last set value...

hope it helps... it is working i have checked....

score 1 · Answer 5 · answered Jun 26 '21 at 06:37

1

maybe you should try to use lambda function if u know what I mean. That does mean: command = lambda: like. I didnt try it but i guess it should work:)

answered Jun 26 '21 at 06:37

Dan Šafránek

39
3

did you mean: `command=lambda: like()` also not necessary if no arguments are passed, so this is probably not the issue – Matiiss Jul 28 '21 at 21:09

score 0 · Answer 6 · answered Jun 25 '21 at 11:34

0

from tkinter import *

root = Tk()

numL = 0
numD = 0

root.geometry("200x100")

def like():
    global numL
    root_label1.config(text=numL+1)
    numL = numL + 1

def dlike():
    global numD
    root_label2.config(text=numD+1)
    numD = numD + 1

root_button1 = Button(root, text="Like", command=like)
root_button2 = Button(root, text="Dislike", command=dlike)

root_label1 = Label(root, text=numL)
root_label2 = Label(root, text=numD)

root_button1.grid(row=0,column=0)
root_button2.grid(row=0,column=1)

root_label1.grid(row=1,column=0)
root_label2.grid(row=1,column=1)

root.mainloop()

Its working !

answered Jun 25 '21 at 11:34

AaYan Yasin

566
3
15

While this works, it is better to avoid globalizing variables, the list method by PCM seems fine. Also it is better to `numD = numD + 1` above `config` and use `+=` as it is more pythonic, and check `+1` inside `config()` too – Delrius Euphoria Jun 25 '21 at 11:35
1

@CoolCloud The list variables used by PCM are also global variables, so your comment *"avoid globalizing variables"* applies to it as well. – acw1668 Jun 25 '21 at 12:00
@acw1668 Ah yea, I did not think of that. Then better to pass parameters – Delrius Euphoria Jun 25 '21 at 12:06

How can i make one function repeat by pressing button several times in Python tkinter?

6 Answers6