I can't figure out how can I finish one simple program written in Python. Program basically generates array of ten random numbers and then sorts them using bubblesort algorithm. Whole shorting process should be shown on screen - such as this one
My current code is this:
import tkinter
import random
canvas = tkinter.Canvas(bg='white',width='800',height='400')
canvas.pack()
c = []
for i in range(0,10):
c=c+[random.randrange(10)]
print(c)
print('Zoradenie...', c)
def sort(c):
x=300
for i in range(0,10):
for j in range(0,len(c)-1-1):
if c[j+1]<c[j]:
c[j+1],c[j]=c[j],c[j+1]
canvas.create_text(300,80,text=c[j],fill='Red')
x+=25
canvas.update()
canvas.after(1000)
print(c)
return c
sort(c)
But I can't figure out how to show numbers on screen. Any ideas?
To display the digits on the canvas, you must create a text item for each digit. See the end of my code. The harder part is moving the digits. One way is to delete and recreate; the other is to move. I choose the latter.
The hardest part, perhaps, is the time delays. If one uses mainloop, one should use after rather than time.sleep (which blocks the looping) and not use for-loops for animation. The problem is that the function (here sort) that naturally contains for-loops must be broken into pieces whose joint operation may be hard to understand. If one is running just one function and does not care about user interaction (for instance, a pause button), one can use time.sleep and update. I have done so here to make what is going on clearer.
from random import randrange
from time import sleep
import tkinter as tk
root = tk.Tk()
canvas = tk.Canvas(root, bg='white', width='800', height='400')
canvas.pack()
ndigits = 10
digits = [randrange(10) for _ in range(ndigits)]
tdelta1, tdelta2 = .8, .2
xstart = 300
xdelta = 25
y = 80
def color(i, swap):
"Temporarily color digits i and i+i according to swap needed."
x = xstart + xdelta * i
dcolor = 'Red' if swap else 'green'
canvas.itemconfigure(items[i], fill=dcolor)
canvas.itemconfigure(items[i+1],fill=dcolor)
canvas.update()
sleep(tdelta1)
canvas.itemconfigure(items[i], fill='Black')
canvas.itemconfigure(items[i+1], fill='Black')
canvas.update()
sleep(tdelta2)
def swap(i):
digits[i], digits[i+1] = digits[i+1], digits[i]
canvas.move(items[i], xdelta, 0)
canvas.move(items[i+1], -xdelta, 0)
items[i], items[i+1] = items[i+1], items[i]
def bubsort():
"Sort digits and animate."
for stop in reversed(range(1, ndigits)):
# stop = index of position whose entry will be determined.
for i in range(stop):
swap_needed = digits[i] > digits[i+1]
color(i, swap_needed)
if swap_needed:
swap(i)
color(i, False)
# Create display items and pause.
items = [canvas.create_text(xstart + xdelta*i, y, text=str(digit))
for i, digit in enumerate(digits)]
canvas.update()
sleep(tdelta1)
bubsort()
This code makes it fairly easy to replace the text digit display with, for instance, a colored bar display. To develop this further, I would define a class of items combining int values and display items as attributes. There would them be only one array of combined items. With comparison methods defines, the array could be passed to any sort function.
Related
Let say I've a list of widgets that are generated by tkinter uisng a loop (it's customtkinter in this case but since tkinter is more well known so I think it'd be better to make an example with it), each widgets lie in the same frame with different label text. Here is an example for the code:
x=0
self.scrollable_frame = customtkinter.CTkScrollableFrame(self, label_text="CTkScrollableFrame")
self.scrollable_frame.grid(row=1, column=2, padx=(20, 0), pady=(20, 0), sticky="nsew")
self.scrollable_frame.grid_columnconfigure(0, weight=1)
self.scrollable_frame_switches = []
for i in range(x,100):
switch = customtkinter.CTkSwitch(master=self.scrollable_frame, text=f"CTkSwitch {i}")
switch.grid(row=i, column=0, padx=10, pady=(0, 20))
self.scrollable_frame_switches.append(switch)
My question is, if the list that help generated those widgets change (in this case it's just a loop ranging from 0-100, might change the widgets text, list size..), what would be the best way for real time update the tkinter window contents?
Ps: I've tried to look for my answer from many places but as of right now, the best answer I can come up with is to update the whole frame with same grid but changed list content, I'll put it bellow. Is there any way better than this? Thank you
Like I said before, while the existing answer might work, it might be inefficient since you are destroying and creating new widgets each time there is a change. Instead of this, you could create a function that will check if there is a change and then if there is extra or less items, the changes will take place:
from tkinter import *
import random
root = Tk()
def fetch_changed_list():
"""Function that will change the list and return the new list"""
MAX = random.randint(5, 15)
# Create a list with random text and return it
items = [f'Button {x+1}' for x in range(MAX)]
return items
def calculate():
global items
# Fetch the new list
new_items = fetch_changed_list()
# Store the length of the current list and the new list
cur_len, new_len = len(items), len(new_items)
# If the length of new list is more than current list then
if new_len > cur_len:
diff = new_len - cur_len
# Change text of existing widgets
for idx, wid in enumerate(items_frame.winfo_children()):
wid.config(text=new_items[idx])
# Make the rest of the widgets required
for i in range(diff):
Button(items_frame, text=new_items[cur_len+i]).pack()
# If the length of current list is more than new list then
elif new_len < cur_len:
extra = cur_len - new_len
# Change the text for the existing widgets
for idx in range(new_len):
wid = items_frame.winfo_children()[idx]
wid.config(text=new_items[idx])
# Get the extra widgets that need to be removed
extra_wids = [wid for wid in items_frame.winfo_children()
[-1:-extra-1:-1]] # The indexing is a way to pick the last 'n' items from a list
# Remove the extra widgets
for wid in extra_wids:
wid.destroy()
# Also can shorten the last 2 steps into a single line using
# [wid.destroy() for wid in items_frame.winfo_children()[-1:-extra-1:-1]]
items = new_items # Update the value of the main list to be the new list
root.after(1000, calculate) # Repeat the function every 1000ms
items = [f'Button {x+1}' for x in range(8)] # List that will keep mutating
items_frame = Frame(root) # A parent with only the dynamic widgets
items_frame.pack()
for item in items:
Button(items_frame, text=item).pack()
root.after(1000, calculate)
root.mainloop()
The code is commented to make it understandable line by line. An important thing to note here is the items_frame, which makes it possible to get all the dynamically created widgets directly without having the need to store them to a list manually.
The function fetch_changed_list is the one that changes the list and returns it. If you don't want to repeat calculate every 1000ms (which is a good idea not to repeat infinitely), you could call the calculate function each time you change the list.
def change_list():
# Logic to change the list
...
calculate() # To make the changes
After calculating the time for function executions, I found this:
Widgets redrawn
Time before (in seconds)
Time after (in seconds)
400
0.04200148582458496
0.024012088775634766
350
0.70701003074646
0.21500921249389648
210
0.4723021984100342
0.3189823627471924
700
0.32096409797668457
0.04197263717651367
Where "before" is when destroying and recreating and "after" is only performing when change is needed.
So I've decided that if I want to click a button, that button should be able to update the list. Hence, I bind a non-related buttons in the widget to this function:
def sidebar_button_event(self):
global x
x=10
self.scrollable_frame.destroy()
self.after(0,self.update())
Which will then call for an update function that store the change value, and the update function will just simply overwrite the grid:
def update(self):
self.scrollable_frame = customtkinter.CTkScrollableFrame(self, label_text="CTkScrollableFrame")
self.scrollable_frame.grid(row=1, column=2, padx=(20, 0), pady=(20, 0), sticky="nsew")
self.scrollable_frame.grid_columnconfigure(0, weight=1)
self.scrollable_frame_switches = []
for i in range(x,100):
switch = customtkinter.CTkSwitch(master=self.scrollable_frame, text=f"CTkSwitch {i}")
switch.grid(row=i, column=0, padx=10, pady=(0, 20))
self.scrollable_frame_switches.append(switch)
I am making a board game with Tkinter. I create a grid:
def create_grid(self):
self.grid_frame = Frame(window)
self.grid_frame.grid(row=1, column=0)
self.grid_picture = PhotoImage(file="grid.PNG")
self.grid_label = Label(self.grid_frame, image=self.grid_picture)
self.grid_label.grid(row=0, column=0, columnspan=100, rowspan=10)
Then the pawns are placed based on their distance from start:
def green_grid_translation(self, green_position):
if green_position < 10:
self.green_grid_row = 9
self.green_grid_column = green_position*10+2
elif green_position < 20:
self.green_grid_row = 8
self.green_grid_column = 92 - (green_position - 10)*10
The pawns are placed on the same frame as the grid, the frame is created again with every move:
def position_interface(self):
self.grid_frame = Frame(window)
self.grid_frame.grid(row=1, column=0)
self.grid_picture = PhotoImage(file="grid.PNG")
self.grid_label = Label(self.grid_frame, image=self.grid_picture)
self.grid_label.grid(row=0, column=0, columnspan=100, rowspan=10)
self.green_picture = PhotoImage(file="green.png")
self.green_symbol = Label(self.grid_frame, image=self.green_picture)
self.green_symbol.grid(row=self.green_grid_row, column=self.green_grid_column)
self.blue_picture = PhotoImage(file="blue.png")
self.blue_symbol = Label(self.grid_frame, image=self.blue_picture)
self.blue_symbol.grid(row=self.blue_grid_row, column=self.blue_grid_column)
The following loops are used to make them go step by step:
for x in reversed(range(green_change[0])):
run_grid.green_grid_translation(green_change[1] - x)
run_grid.blue_grid_translation(blue_change[1])
run_grid.position_interface()
window.update()
sleep(1)
for x in reversed(range(blue_change[0])):
run_grid.green_grid_translation(green_change[1])
run_grid.blue_grid_translation(blue_change[1] - x)
run_grid.position_interface()
window.update()
sleep(1)
green_change[0] is the number of steps the pawn is supposed to move,
green_change[1] is its position on the grid
It works fine with a single pawn, but when there are two, it's like the number
of rows and columns changes and the pawns sometimes land in wrong positions:
Is there a way to fix it or do I need to take a completely different approach?
Your approach is wrong. There is plenty of stuff to improve, e.g the use of sleep in a GUI application is an absolute no-no.
But for the problem at hand, you simply use the wrong abstraction. Grids are for creating widgets in regular spaced layouts. But not for stacking/rearranging them. It CAN be done, but I would advise against it.
Use instead a canvas. This allows you to simply overlay graphical elements, and even move them around (smoothly if you are so inclined!).
So, what I am trying to do is when you open the window, it starts a process in which every 0.2 seconds it changes the first and 3rd value of the color (in which it converts the elements of the range into a hex value and then a string) to go from rgb( 86, 32, 86) to rgb(126, 32, 126). Although I thought this might just work, it doesn't. I only get a background of the first color and that's all.
from tkinter import *
import time
root = Tk()
for i in range(86,126):
h = hex(i)
h = str(h)
h = h[2] + h[3]
root.configure(background=("#" + h + "32" + h ))
time.sleep(0.2)
root.mainloop()
You must use the after function to give the window system time to process updates. Calling window update functions in a loop like that on the main thread will lock up the window until the loop terminates.
Try moving the code in the for loop into a new function, say updateBackground, and making it call itself recursively using after:
def updateBackground(i):
# ...
if i < 126:
root.after(200, lambda: updateBackground(i + 1))
Note that I used a lambda in order to increment i.
Credit: https://stackoverflow.com/a/36670519/1757964
Your main issue with this code is the use of sleep(). Because Tkinter is a single thread application and is event driven what ends up happening when you use sleep() the entire Tkinter instance freezes.
To work around this Tkinter provides a method called After() that is designed to schedule an event to happen after a time. So to get the same affect you are trying to get with sleep we can instead create a function that can call itself after 0.2 sec and provide it with the starting number and ending number.
from tkinter import *
root = Tk()
def do_something(start_number, end_number):
if start_number <= end_number:
h = str(hex(start_number))[2:] # combined all your work on h to one line
root.configure(background=("#{}32{}".format(h, h)))
start_number += 1
root.after(200, do_something, start_number, end_number)
do_something(86, 126)
root.mainloop()
Note that the color change is mild and hard to see. If you increase the `end_number thought it will become more obvious.
I am beginning GUI in Python 3.5, and I am trying to setup a simple qwerty keyboard. Based on the examples, I tried the following code
from tkinter import Tk, Label, RAISED, Button, Entry
self.window = Tk()
#Keyboard
labels = [['q','w','e','r','t','y','u','i','o','p'],
['a','s','d','f','g','h','j','k','l'],
['z','x','c','v','b','n','m','<']]
n = 10
for r in range(3):
for c in range(n):
n -= 1
label = Label(self.window,
relief=RAISED,
text=labels[r][c])
label.grid(row=r,column=c)
continue
This gives me the first row, but it does not return anything else. I tried simply using 10 as the range, which created the first two rows of the keyboard, but it still did not continue onto the last row.
Your issue is in the line n -= 1. Every time a label is created, you make n one less- after the first whole row, n==0, and thus the range is 0>0, and ranges never include the high bound- for c in range(0) will just drop from the loop (as it has looped through all the nonexistent contents).
A better solution involves iterating through the lists instead of through the indexes- for loops take any iterable (list, dictionary, range, generator, set, &c.);
for lyst in labels:
# lyst is each list in labels
for char in lyst:
# char is the character in that list
label = Label(... text=char) # everything else in the Label() looks good.
label.grid(...) # You could use counters for this or use ennumerate()-ask if you need.
# The continue here was entirely irrelevant.
Is this what you want it to do? Let me know if you need me to explain it further but basically what I'm doing is first filling the columns in each row. So row remains 0 and then as I loop through the column (the inner list) I fill in each of the keys, then on to the next row and etc.
from tkinter import Tk, Label, RAISED, Button, Entry
window = Tk()
#Keyboard
labels = [['q','w','e','r','t','y','u','i','o','p'],
['a','s','d','f','g','h','j','k','l'],
['z','x','c','v','b','n','m','<']]
for r in labels:
for c in r:
label = Label(window, relief=RAISED, text=str(c))
label.grid(row=labels.index(r), column=r.index(c))
window.mainloop()
I am getting problems with Tkinter after() method.
Actually, what I want to do is to change the background colour of some entry boxes as soon as times passes. Let's take this piece of code (which is different from the script I'm working on, but the situation described is the same):
import Tkinter as tk
root = tk.Tk()
root.option_add("*Entry.Font","Arial 32 bold")
emptyLabel=tk.Label()
emptyLabel.grid(row=4) #Empty label for geometry purpose
entryList=[]
for x in range(4):
entryList.append([])
for y in range(4):
entryList[x].append('')
entryList[x][y]=tk.Entry(root, bg="white",width=2,justify="center",
takefocus=True,insertofftime=True)
entryList[x][y].grid(row=x,column=y)
solvebt=tk.Button(root,text='Solve').grid(row=5,column=2)
newgamebt=tk.Button(root,text='New').grid(row=5,column=1)
#BROKEN PART STARTS HERE
def changebg(x,y):
entryList[x][y]['bg']='yellow'
for x in range(4):
for y in range(4):
entryList[x][y].after(300,changebg(x,y))
#Same result with root.after(300,changebg(x,y))
root.mainloop()
The problem is that when I start the program, I would expect it to show me as it "paints", one at time, all of the entry boxes in yellow. What happens, instead, is that the program freezes for (300*16) milliseconds and then, all of a sudded, every entry boxes is yellow!
The problem is here:
def changebg(x,y):
entryList[x][y]['bg']='yellow'
for x in range(4):
for y in range(4):
entryList[x][y].after(300,changebg(x,y))
#Same result with root.after(300,changebg(x,y))
You're calling changebg to immediately in the double for loop -- You're then passing the return value (None) to root.after. This won't lead to the delay that you describe. Perhaps your actual code looks like:
for x in range(4):
for y in range(4):
entryList[x][y].after(300,lambda x=x,y=y : changebg(x,y))
That will lead to the behavior you actually describe. Ultimately, what you need is to flatten your list of widgets and then pass then one at a time -- registering the next one if it exists:
import itertools
all_entries = itertools.chain.from_iterable(entryList)
def changebg(ientries):
ientries = iter(ientries) #allow passing a list in as well ...
entry = next(ientries,None)
if entry is not None:
entry['bg'] = 'yellow' #change the color of this widget
root.after(300,lambda : changebg(ientries)) #wait 300ms and change color of next one.
changebg(all_entries)