Can't cycle elements in array into buttons using tkinter

Question

myButtons = [
    "E", "CE", "C", "/", "%",
    "7", "8", "9", "*", "x²",
    "4", "5", "6", "-", "√",
    "1", "2", "3", "+", "^",
    "0", ".", "+/-", "!", "="
]

for i in myButtons:
    for j in range(0,4):
        for k in range(0,4):
            tkinter.Button(window, text=i,bg="blue", width=10, height=3, command=echo(i)).grid(row=j, column=k)

Can't cycle array elements into buttons, i expected buttons with value from array, but got last element as value of many buttons. Why it is happening?

vestronge · Accepted Answer · 2020-07-21 12:08:13Z

4

I think you wanted to do this

myButtons = [
    ["E", "CE", "C", "/", "%"],
    ["7", "8", "9", "*", "x²"],
    ["4", "5", "6", "-", "√"],
    ["1", "2", "3", "+", "^"],
    ["0", ".", "+/-", "!", "="]
]

for j, row in enumerate(myButtons):
    for k, i in enumerate(row):
            tkinter.Button(window, text=i,bg="blue", width=10, height=3, command=echo(i)).grid(row=j, column=k)

Note, I have changed myButtons to a list of lists as I am assuming this is a static list. If you want to use original list, we can refactor the solution by getting the quotient and remainder on division by 5 as j and k respectively

answered Jul 21, 2020 at 12:08

vestronge

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Comments

Splitter · Accepted Answer · 2020-07-21 12:39:56Z

1

I suggest such a code:

import tkinter as tk
from tkinter import messagebox


def echo(text):
    tk.messagebox.showinfo('info', text)

root = tk.Tk()
myButtons = [
    "E", "CE", "C", "/", "%",
    "7", "8", "9", "*", "x²",
    "4", "5", "6", "-", "√",
    "1", "2", "3", "+", "^",
    "0", ".", "+/-", "!", "="
]

for i, text in enumerate(myButtons):
    tk.Button(root, text=text, bg="blue",
              width=10, height=3,
              command=lambda t=text: echo(t)).grid(row=i//5, column=i % 5)
root.mainloop()

edited Jul 21, 2020 at 12:39

answered Jul 21, 2020 at 12:12

Splitter

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10 Comments

Splitter Over a year ago

@Imperions your code doesn't work properly because you are going to create 16 buttons for every myButtons element. I. e. 16 buttons for "E", 16 for "CE" and so on.

Splitter Over a year ago

@Imperions also echo(i) is a mistake probably. You should put a function there, without (). If you need to pass arguments in, then you can use a lambda this way: command=lambda i: echo(i)

Imperions Over a year ago

it returns error: TypeError: <lambda>() missing 1 required positional argument: 'i'

Splitter Over a year ago

@Imperions oh, sorry, my bad. I fixed it and updated my answer.

Splitter Over a year ago

@Imperions a function passed to command parameter would take no arguments when the click event occurs. So we use a named argument (t=text) in order to 'transport' the text variable into the lambda. The lambda works as a delegate to echo function. It's a common trick to pass arguments to event handlers.

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