记录合并排序的执行

Question

我在Python中实现了合并排序......

def mergesort(z):
    if len(z) > 1:
        mid = len(z)//2
        leftPortion = z[:mid]
        rightPortion = z[mid:]
        mergesort(leftPortion)
        mergesort(rightPortion)
        l = 0 # Next position in rightPortion
        r = 0 # Next position in leftPortion
        i = 0 # Next position in z
        while l < len(leftPortion) and r < len(rightPortion):
            if leftPortion[l] <= rightPortion[r]:
                z[i] = leftPortion[l]
                l = l + 1 
            else:
                z[i] = rightPortion[r]
                r = r + 1
            i = i + 1 
        while l < len(leftPortion):
            z[i] = leftPortion[l]
            l = l + 1
            i = i + 1
        while r < len(rightPortion):
            z[i] = rightPortion[r]
            r = r + 1
            i = i + 1

...我希望'记录'原始列表的状态，z，因为排序执行所以我可以使用Matplotlib来绘制排序的动画。我已经为冒泡排序和插入排序实现了这个方法，但由于合并中的递归，无法弄清楚如何做到这一点。有人可以帮忙吗？

这就是我使用冒号排序的方式......

import matplotlib.pyplot as plot
from time import sleep
from random import shuffle
from copy import copy
from time import time

plot.ion()

def generatecolours(w):
    max = 16581375 # 255**3
    interval = int(max/len(w))
    r = range(0,max,interval)
    return ['#{0}'.format(hex(r[i])[2:].zfill(6)) for i in w]

def plotchart(x,y,title):
    plot.clf()
    plot.title(title)
    plot.axis('off')
    plot.bar(x,y,color=generatecolours(y))
    plot.pause(0.0001)
    sleep(pause)

def bubblesort():
    n = len(z)
    trace = [copy(z)]
    while True:
        swap = False
        for i in range(n-1):
            if z[i] > z[i+1]:
                z[i],z[i+1] = z[i+1],z[i]
                swap = True
            trace.append(copy(z))
        n = n - 1
        if not swap or n == 1:
            break
    return trace

# Define number of items in the list
items = 16

# Pause between iterations (s)
pause = 0.2

# Define coordinates and shuffle y
x = [i for i in range(1,items+1)]
y = [i for i in range(1,items+1)]
shuffle(y)

# Time sort operation for copies of y
print('Bubble sort')
print('-----------')
z = copy(y)
print('Unsorted list : {0}'.format(','.join(map(str,z))))
plotchart(x,z,'Bubble Sort')
input('Press enter to start ...')
start = time()
trace = bubblesort()
for line in trace:
    plotchart(x,line,'Bubble Sort')
print('Time elapsed : {:.3f}s'.format(time()-start))
print('Sorted list   : {0}\n'.format(','.join(map(str,z))))
input('Press enter when ready ...')

感谢您的帮助。