Python tkinter listbox data type and format

Question

(I placed a similar question not too long ago but received no real answer).

I have a simple Python (3.5) data List that I fill up a listbox with. When I read back selected elements from the listbox, while I can make the output look like a Python list, it does not really behave like a list, and I am unable to address elements in the list. It seems as if the list appears as a string of chars.

The question is simply how can one save a list (integers in my case) in a listbox and read back selected elements as a new viable list of the selected elements.

Here is a working demonstration of the problem:

import tkinter as tk
from tkinter import *

root = tk.Tk()

global listbox
global indatalist

indatalist = [[0, 66, 42], [553, 68, 124], [1106, 64, 3], [3321, 78, 8], [3878, 112, 102]]

listbox = tk.Listbox(root,font = 'TkFixedFont',selectmode=EXTENDED)


def Set():  # Populate the listbox:
    global listbox
    global indatalist
    print('indatalist[1][1]=',indatalist[1][1]) # Nicely prints a 2 dim list
    listbox.delete(0,'end')  # Clear the listbox
    # Populate the listbox
    for index, inlist in enumerate(indatalist):
        listbox.insert(len(indatalist),(indatalist[index][0],indatalist[index][1],indatalist[index][2]))

    listbox.pack()

def Get():  # Read back the listbox
    global listbox
    selecteddata = listbox.selection_get()
##    print(selecteddata)
    selecteddata = '[[' + (selecteddata.replace(' ',', ').replace('\n','], [') + ']]')

    """Next option is OK, but can only select one single block"""
##    startindex = min(listbox.curselection())
##    endindex = max(listbox.curselection())
##    selecteddata = listbox.get(startindex,endindex)

    """Next looks like a list of items, but acts as a list of chars"""
    print('selecteddata=',selecteddata)
    print('selecteddata[1][1]=')
    print(selecteddata[1][1]) # Error!. Can not read 2 dim list



stepbutton = tk.Button(root, text = "Set List", command = Set)
stepbutton.pack()

readbutton = tk.Button(root, text = "Get List", command = Get)
readbutton.pack()

root.mainloop()

are you asking how to store a list in each element or how to show each element of a list as an item in a listbox? — Bryan Oakley
– Bryan Oakley, Commented Oct 30, 2018 at 11:53

Bryan Oakley · Accepted Answer · 2018-10-30 14:22:30Z

1

selection_get is not designed to get back the data that is in the listbox. Instead, it is designed to get the X selection, which is by definition a string.

If you want to get the data out of the listbox in the same format that went into the listbox, use the get method.

Here's a simple example of a list comprehension:

selecteddata = [listbox.get(index) for index in listbox.curselection()]

edited Oct 30, 2018 at 14:22

answered Oct 30, 2018 at 11:55

Bryan Oakley

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3 Comments

samtal Over a year ago

Thanks, but your answer does not seem to be accurate (or I am missing something): As can be seen in my example, I can get back any block from the entire list by listbox.curselection() for a selected section. What I need is to select several random items from the listbox and present as a new list. I can get the itmes as requested, but I do not know how to make the selected items a list. Please, try the code also with the listbox.curselection() option.

Bryan Oakley Over a year ago

@samtal: my apologies. I misunderstood the question. I've rewritten my answer to be more accurate.

samtal Over a year ago

Thanks Bryan. Solved the problem simple and easy.

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