通过使用 Python 读取数字 txt 文件进行快速排序

Question

I have updated my program, it did not give me an error. However it gave me the same txt file without sorting

txt_array.txt 54044 14108 79294 29649 25260 60660 2995 53777 49689 9083

#QuickSort with first element to be a pivot element

def choosePivot(arr, l, r): 
        i = (l - 1) #first index
        pivot = arr[l] #first element to be a pivot
    
        for j in range(l+1, r+1):
                if arr[j] < pivot:
                    arr[i], arr[j] = arr[j], arr[i] #swapping
                    i=i+1 #increment i
        position = i-1 #checking position
        arr[l], arr[r] = arr[position], arr[l]
        return position

def quickSort(arr, l, r):
    if len(arr) == 1:
        return arr
    if l < r:
        p = choosePivot(arr, l, r)
        quickSort(arr, l, p-1)
        quickSort(arr, p+1, r)

def readFile(filename, l):
    # f = open(filename, "r")
    with open(filename, "r") as f:
        for line in f:
            l.append(int(line))

    if f.closed == False:
        f.close()

def main ():
    txt_array = []
    size = len(txt_array)
    readFile("array.txt", txt_array)
    print (txt_array[:]) #Appear all numbers of the array
    print ("Numbers of given: " + str(len(txt_array)))
    quickSort(txt_array, 0,size-1)
    print("Sorted array: " + str(txt_array))
    return 0 
main()

my outpout is

[54044, 14108, 79294, 29649, 25260, 60660, 2995, 53777, 49689, 9083]

Numbers of given: 10

Sorted array: [54044, 14108, 79294, 29649, 25260, 60660, 2995, 53777, 49689, 9083]

Answer 1

Error should specify line number, but I suspect it's:

C,txt_array = quickSort(txt_array, 0,size-1)

In this line you unpack whatever quickSort returned, which might be None in which case it would fail with that error.

Answer 2

I suppose you get it on the line C, txt_array = quickSort(txt_array, 0, size-1) , am i right?

In the line C, txt_array = quickSort(txt_array, 0, size-1) you are trying to unpack the returned value into to variables C and txt_array which throws the error you mention since the function doesn't return any value, meaning it is None .

To solve it : Since the function operates on an array that is in the same scope, it should be enough to replace C, txt_array = quickSort(txt_array, 0, size-1) with quickSort(txt_array, 0, size-1) and txt_array should still be sorted. (However, i can't answer on what C is expected to be so that you would need to fix separately)

EDIT: in the example below i substituted the code in your quicksort and choosePivot functions against functions from this tutorial and then the principle i explain in my answer below is illustrated.

# ------- START code borrowed from tutorial
def partition(arr, low, high): 
    i = (low-1)
    pivot = arr[high]
    for j in range(low, high):
        if arr[j] <= pivot: 
            i = i+1
            arr[i], arr[j] = arr[j], arr[i] 
    arr[i+1], arr[high] = arr[high], arr[i+1] 
    return (i+1) 
  
def quickSort(arr, low, high): 
    if len(arr) == 1: 
        return arr 
    if low < high: 
        pi = partition(arr, low, high) 
        quickSort(arr, low, pi-1) 
        quickSort(arr, pi+1, high) 

# ------- END code borrowed from tutorial

def readFile(filename, l):
    with open(filename, "r") as f:
        for line in f:
            l.append(int(line))

    if f.closed == False:
        f.close()

  
def main():
    txt_array = []
    readFile("array.txt", txt_array)
    size = len(txt_array)
    print (txt_array[:]) #Appear all numbers of the array
    print ("Numbers of given: " + str(len(txt_array)))
    quickSort(txt_array, 0, size-1)
    print("Sorted array: " + str(txt_array))

main()

This would output

[54044, 14108, 79294, 29649, 25260, 60660, 2995, 53777, 49689, 9083]
Numbers of given: 10
Sorted array: [2995, 9083, 14108, 25260, 29649, 49689, 53777, 54044, 60660, 79294]