Python GTK update label

Question

I'm completely new to GTK programming in python. I want to solve the following task: After clicking a START button, 20 random numbers should be generated, and be shown in the window. The time between each number is increasing.

Of course getting the random numbers is not a problem, but only the last number is shown in my label. However, the print num command shows, that the numbers are generated the way I want them to be generated. How can I show the numbers in the label now?

Thanks a lot,

Josef

My code looks the following:

import time as t
import random as rd
import math 
import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk, GLib


class MyWindow(Gtk.Window):

    def __init__(self):
        Gtk.Window.__init__(self, title="Window 1")

        box = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=10)
        box.set_homogeneous(False)

        self.label1 = Gtk.Label()
        box.pack_start(self.label1, True, True, 0)

        button = Gtk.Button(label="Start")
        button.connect("clicked", self.on_button_clicked)
        box.pack_start(button, True, True, 0)

        self.add(box)

    def on_button_clicked(self, widget):
        itr=20
        for i in range(itr):
            waittime=(float(i)/float(itr)*1)**3
            num=rd.randint(1,10)
            print num
            self.label1.set_text(str(num))
            t.sleep(waittime)

win = MyWindow()
win.connect("destroy", Gtk.main_quit)
win.show_all()


Gtk.main()

Answer 1

You are not allowing/forcing Gtk to update the label text. For example:

import time as t
import random as rd
import math 
import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk, GLib


class MyWindow(Gtk.Window):

    def __init__(self):
        Gtk.Window.__init__(self, title="Window 1")

        box = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=10)
        box.set_homogeneous(False)

        self.label1 = Gtk.Label()
        box.pack_start(self.label1, True, True, 0)

        button = Gtk.Button(label="Start")
        button.connect("clicked", self.on_button_clicked)
        box.pack_start(button, True, True, 0)

        self.add(box)

    def on_button_clicked(self, widget):
        itr=20
        for i in range(itr):
            waittime=(float(i)/float(itr)*1)**3
            num=rd.randint(1,10)
            print num
            self.label1.set_text(str(num))
            while Gtk.events_pending():
                Gtk.main_iteration()
            t.sleep(waittime)

win = MyWindow()
win.connect("destroy", Gtk.main_quit)
win.show_all()


Gtk.main()