Why button to remove duplicates doesn't work?

Question

Here is some code I wrote, program to contain words.

There's a button supposedly to remove duplicate words, but it won't work.

Please, why is it so?

The problem:

import tkinter as tk

def remove_dups(x):
    list(dict.fromkeys(x))
    update_display()

def update_display():
    words_show.config(text="\n".join(words_list))

words_list = ["Banana", "Banana", "Bnanana"]

root = tk.Tk()
root.title("Word showoff")

words_show = tk.Label(root, text="\n".join(words_list), justify="left", width=30)
words_show.pack()

remove_dups_button = tk.Button(root, text="Remove dups", command=remove_dups(words_list))
remove_dups_button.pack()

root.mainloop()

Full code:

import tkinter as tk

def add_word():
    word = entry.get()
    if word:
        words_list.append(word)
        entry.delete(0, tk.END)
        update_display()

def remove_dups(x):
    list(dict.fromkeys(x))
    update_display()

def update_display():
    words_show.config(text="\n".join(words_list))

def close_program():
    root.quit()

words_list = ["Banana", "Banana", "Bnanana"]

#####

root = tk.Tk()
root.title("Word showoff")

entry = tk.Entry(root, width=30)
entry.pack()

add_button = tk.Button(root, text="Add Word", command=add_word)
add_button.pack()

words_show = tk.Label(root, text="\n".join(words_list), justify="left", width=30)
words_show.pack()

remove_dups_button = tk.Button(root, text="Remove dups", command=remove_dups(words_list))
remove_dups_button.pack()

close_button = tk.Button(root, text="Close", command=close_program)
close_button.pack()

#####

root.mainloop()

I made a function that would update the words list removing the duplicates by turning elements into dictionary keys and then back into a list, and as a separate line of code it worked, but when I tried to make it into a function and call using a Tkinter button it wouldn't do nothing.

Answer 1

It is because remove_dups(x) doesn't update the passed list x, so nothing will be updated.

Just set the unique keys back to the passed list as below:

def remove_dups(x):
    # set the unique keys back to the list
    x[:] = list(dict.fromkeys(x))
    update_display()

Also command=remove_dups(words_list) should be command=lambda: remove_dups(words_list).

Answer 2

import tkinter as tk

def add_word():
    word = entry.get()
    if word:
        words_list.append(word)
        entry.delete(0, tk.END)
        update_display()

def remove_dups():
    global words_list
    words_list = list(dict.fromkeys(words_list))
    update_display()

def update_display():
    words_show.config(text="\n".join(words_list))

def close_program():
    root.quit()

words_list = ["Banana", "Banana", "Bnanana"]

#####

root = tk.Tk()
root.title("Word showoff")

entry = tk.Entry(root, width=30)
entry.pack()

add_button = tk.Button(root, text="Add Word", command=add_word)
add_button.pack()

words_show = tk.Label(root, text="\n".join(words_list), justify="left", width=30)
words_show.pack()

# Fix: Use lambda to delay function execution
remove_dups_button = tk.Button(root, text="Remove dups", command=lambda: remove_dups())
remove_dups_button.pack()

close_button = tk.Button(root, text="Close", command=close_program)
close_button.pack()

#####

root.mainloop()

I think the issue is with how you're calling the remove_dups function. To fix it, you could pass the function reference (without calling it) using a lambda function or a partial function from the functools module.

Answer 3

import tkinter as tk

def add_word():
    word = entry.get()
    if word:
        words_list.append(word)
        entry.delete(0, tk.END)
        update_display()

def remove_dups(x):
    global words_list  # Ensure we modify the global variable
    words_list = list(dict.fromkeys(x))  # Remove duplicates and update the list
    update_display()  # Refresh the UI

def update_display():
    words_show.config(text="\n".join(words_list))

def close_program():
    root.quit()

words_list = ["Banana", "Banana", "Bnanana"]

root = tk.Tk()
root.title("Word showoff")

entry = tk.Entry(root, width=30)
entry.pack()

add_button = tk.Button(root, text="Add Word", command=add_word)
add_button.pack()

words_show = tk.Label(root, text="\n".join(words_list), justify="left", width=30)
words_show.pack()

remove_dups_button = tk.Button(root, text="Remove dups", command=lambda: remove_dups(words_list))
remove_dups_button.pack()

close_button = tk.Button(root, text="Close", command=close_program)
close_button.pack()

root.mainloop()

1. The remove_dups function does not modify words_list In your remove_dups function, you create a new list but do not assign it back to words_list. This means words_list remains unchanged.

2. The Button Calls the Function Immediately Instead of on Click You're calling remove_dups(words_list) immediately when the script runs, instead of passing a reference to the function.

Fix: Use lambda to Delay Execution