如何在 python tkinter 中正確實現冒泡排序算法？

Question

我正在寫一系列關於排序算法的文章，第一部分是關於冒泡排序的，我有 GUI 元素，但是排序算法本身不能正常工作。 它隨機交換一系列不同長度的行，但排序沒有按預期工作。 它是用 python Tkinter 編寫的，我認為主要問題出在我如何像兩個列表一樣編程排序，一個在屏幕上，一個在 memory 上。 如果您也可以向我解釋我的錯誤，那將會很有幫助。

import tkinter as tk
import random


def swap_two_pos(pos_0, pos_1):
    """This does the graphical swapping of the rectangles on the canvas
    by moving one rectangle to the location of the other, and vice versa
    """    
    x_00, _, x_01, _ = canvas.coords(pos_0)
    x_10, _, x_11, _ = canvas.coords(pos_1)
    # moves each rectangle to the x position of the other; y remains unchanged
    canvas.move(pos_0, x_10-x_00, 0)
    canvas.move(pos_1, x_01-x_11, 0)

def sort_two(pos_0, pos_1):
    x_00, y1, x_01, _ = canvas.coords(pos_0)
    x_10, y2, x_11, _ = canvas.coords(pos_1)
    # moves each rectangle to the x position of the other; y remains unchanged
    if y2 > y1:
        canvas.move(pos_0, x_10-x_00, 0)
        canvas.move(pos_1, x_01-x_11, 0)

def rand_sort():
    for i in range(50000):
        rd1 = random.randint(0, 58)
        rd2 = random.randint(0, 58)
        pos_1 = barList[rd1]
        pos_2 = barList[rd2]
        sort_two(pos_1, pos_2)
        barList[rd1], barList[rd2] = barList[rd2], barList[rd1]



def sort ():
    n = len(barList)
  
    # Traverse through all array elements 
    for i in range(n): 
  
        # Last i elements are already in place 
        for j in range(0, n-i-1):
                sort_two(barList[j], barList[j+1])
                barList[j], barList[j+1] = barList[j+1], barList[j]
        else:
            break

def random_swap():
    """Not a sort yet, but you have the bare bones operations
    so the swap is executed
    """
    for i in range(500):
        rd1 = random.randint(0, 58)
        rd2 = random.randint(0, 58)
        pos_0 = barList[rd1]
        pos_1 = barList[rd2]
        
        swap_two_pos(pos_0, pos_1)
        # it is necessary to swap the values in the list too
        barList[rd1], barList[rd2] = barList[rd2], barList[rd1]

window = tk.Tk()
window.title('Sorting')
window.geometry('600x400')

# button to command the swap
tk.Button(window, text='swap', command=random_swap).pack()
tk.Button(window, text='sort', command=sort).pack()

xstart = 5
xend = 15
canvas = tk.Canvas(window, width='900', height='900')
canvas.pack()
barList = []
lengthList = []
Y = 5

for x in range(1,60):
    bar = canvas.create_rectangle(xstart, Y, xend, 395, fill='red')
    barList.append(bar)
    xstart += 10
    xend += 10
    Y += 5

for bar in barList:
    x = canvas.coords(bar)
    length = x[3]-x[1]
    lengthList.append(length)

window.mainloop()

Answer 1

最大的問題是在sort_two里面你有if

if y2 > y1:
    canvas.move(pos_0, x_10-x_00, 0)
    canvas.move(pos_1, x_01-x_11, 0)

僅當y2 > y1時才替換元素

但是在sort_two()之后你使用barList

sort_two(pos_1, pos_2)
barList[rd1], barList[rd2] = barList[rd2], barList[rd1]

它總是替換列表中的元素。

這樣你在屏幕上就會得到錯誤的結果。

您可以從sort_two()返回True/False以控制何時更改barList上的元素

if y2 > y1:
    canvas.move(pos_0, x_10-x_00, 0)
    canvas.move(pos_1, x_01-x_11, 0)
    return True
else:
    return False

和

if sort_two(pos_1, pos_2):
    barList[rd1], barList[rd2] = barList[rd2], barList[rd1]

---

這里最終代碼

我使用簡單的計算來替換 canvas 上的元素

x1, _, _, _ = canvas.coords(pos_0)
x2, _, _, _ = canvas.coords(pos_1)

diff = x1 - x2

canvas.move(pos_0, -diff, 0)
canvas.move(pos_1, +diff, 0)

我也刪了

 else:
    break

每次替換后都會停止 animation 並且它需要一次又一次地單擊按鈕sort - 我使用

    window.update()
    time.sleep(0.1)

所以它顯示 animation （慢慢地）到排序結束，我不必單擊按鈕sort

import tkinter as tk
import random
import time

def swap_two_pos(pos_0, pos_1):
    """This does the graphical swapping of the rectangles on the canvas
    by moving one rectangle to the location of the other, and vice versa
    """    
    
    x1, _, _, _ = canvas.coords(pos_0)
    x2, _, _, _ = canvas.coords(pos_1)
    
    diff = x1 - x2

    canvas.move(pos_0, -diff, 0)
    canvas.move(pos_1, +diff, 0)

def sort_two(pos_0, pos_1):
    x1, y1, _, _ = canvas.coords(pos_0)
    x2, y2, _, _ = canvas.coords(pos_1)

    diff = x1 - x2

    # moves each rectangle to the x position of the other; y remains unchanged
    if y2 > y1:
        canvas.move(pos_0, -diff, 0)
        canvas.move(pos_1, +diff, 0)
        return True
    else:
        return False

def rand_sort():
    for i in range(50000):
        rd1 = random.randint(0, 58)
        rd2 = random.randint(0, 58)
        pos_1 = barList[rd1]
        pos_2 = barList[rd2]
        if sort_two(pos_1, pos_2):
            barList[rd1], barList[rd2] = barList[rd2], barList[rd1]

def sort ():
    n = len(barList)
  
    # Traverse through all array elements 
    for i in range(n): 
  
        # Last i elements are already in place 
        for j in range(0, n-i-1):
            if sort_two(barList[j], barList[j+1]):
                barList[j], barList[j+1] = barList[j+1], barList[j]
            
        window.update()
        time.sleep(0.1)
        
        
def random_swap():
    """Not a sort yet, but you have the bare bones operations
    so the swap is executed
    """
    for i in range(500):
        rd1 = random.randint(0, 58)
        rd2 = random.randint(0, 58)
        pos_0 = barList[rd1]
        pos_1 = barList[rd2]
        
        swap_two_pos(pos_0, pos_1)
        # it is necessary to swap the values in the list too
        barList[rd1], barList[rd2] = barList[rd2], barList[rd1]

window = tk.Tk()
window.title('Sorting')
window.geometry('600x400')

# button to command the swap
tk.Button(window, text='swap', command=random_swap).pack()
tk.Button(window, text='sort', command=sort).pack()

xstart = 5
xend = 15
canvas = tk.Canvas(window, width='900', height='900')
canvas.pack()
barList = []
lengthList = []
Y = 5

for x in range(1,60):
    bar = canvas.create_rectangle(xstart, Y, xend, 395, fill='red')
    barList.append(bar)
    xstart += 10
    xend += 10
    Y += 5

for bar in barList:
    x = canvas.coords(bar)
    length = x[3]-x[1]
    lengthList.append(length)

window.mainloop()