Bubble sort not sorting in Python

Question

I've started trying to use python again for some simple code, where before I've only really used p5.js. I'm trying to code a bubble sort and after making a working bubble sort, I copied part of the code into another code to implement into First Fit decreasing bin packing. Now with minimal changes, the sort isn't working where it would before. I only changed it to perform all bubble sorts until it is sorted instead of once at a time with user input in between. The new code does not sort the items correctly and often sorts the highest number on the list into the middle. I tried this with numbers including 108 and 20 and 108 was always after 20 even though it's a decreasing sort. The bubble function I use is

def bubble(x):
y = []
i = 0
k = 1
while i + k < len(x):
    if x[i] < x[i + k]:
        y.append(x[i + k])
        k = k + 1
    else:
        y.append(x[i])
        i = i + k
        k = 1
y.append(x[i])
return y

The original code is:

    numbers = []
len = int(input("How many numbers are there? "))

for i in range(0, len):
    current = str(i + 1)
    num = int(input("Number " + current + " "))
    numbers.append(num)

print("Here are your numbers:")
print(numbers)

bubbling = False

def bubble(x):
    y = []
    i = 0
    k = 1
    while i + k < len:
        if x[i] < x[i + k]:
            y.append(x[i + k])
            k = k + 1
        else:
            y.append(x[i])
            i = i + k
            k = 1
    y.append(x[i])
    return y

cont = input("Bubble? (Y/N) ")
if cont == "Y":
    bubbling = True

while bubbling == True:
    previous = numbers
    numbers = bubble(numbers)

    if numbers == previous:
        end = input("The bubble sort has been finished" )
        bubbling = False
        break

    print(numbers)

    cont = input("Bubble? (Y/N) ")

    if cont == "Y":
        continue
    else:
        break

and my second iteration is: (numbers are just input one at a time and enter nothing for it to bubble)

listing = True
bubbling = True

temp_array = []

# if an input is empty, stop adding numbers to the array and add bin size (LATER)

while listing:
    temp_number = input()
    if temp_number:
        temp_array.append(temp_number)
    else:
        listing = False
        break


print(temp_array)


def bubble(x):
    y = []
    i = 0
    k = 1
    while i + k < len(x):
        if x[i] < x[i + k]:
            y.append(x[i + k])
            k = k + 1
        else:
            y.append(x[i])
            i = i + k
            k = 1
    y.append(x[i])
    return y


while bubbling:
    prev_array = temp_array
    temp_array = bubble(prev_array)
    if temp_array == prev_array:
        bubbling = False
        break

print(temp_array)

First, can you give us a complete example? " I tried this with numbers including 108 and 20" isn't a complete example unless bubble([108, 20]) actually returns [20, 108], which it doesn't. — abarnert
– abarnert, Commented Jul 17, 2018 at 0:29
Anyway, it looks like your problem isn't in your bubble sort, but in your input. temp_number = input() will give you a string. If you sort the strings '108' and '20', then '20' > '108', because strings are compared character by character, dictionary-style: '2' > '1', so '20' is bigger. You just need temp_number = int(input()) or something similar somewhere. If you understand that and it's just a simple oversight, we can close this question as a typo; if you need further explanation, we can find a duplicate with a detailed answer. — abarnert
– abarnert, Commented Jul 17, 2018 at 0:31
As a side note, why are you implementing a bubble sort in the first place? If you're doing it as an exercise, you should probably write a test driver that compares bubble(x) to sorted(x) for a variety of different x lists. If you just need some numbers sorted, just call sorted instead of implementing your own less-efficient sort. — abarnert
– abarnert, Commented Jul 17, 2018 at 0:33
That makes so much sense! Thank you very much, I wanted to make sure in the second version that not just integers could be included but forgot about string conversion. — Diogo Santos
– Diogo Santos, Commented Jul 17, 2018 at 0:35

16dhudson 16dhudson · Accepted Answer · 2021-03-22 10:13:38Z

-2

numbers = []
len = int(input("How many numbers are there? "))

for i in range(0, len):
    current = str(i + 1)
    num = int(input("Number " + current + " "))
    numbers.append(num)

print("Here are your numbers:")
print(numbers)

bubbling = False

def bubble(x):
    y = []
    i = 0
    k = 1
    while i + k < len:
        if x[i] < x[i + k]:
            y.append(x[i + k])
            k = k + 1
        else:
            y.append(x[i])
            i = i + k
            k = 1
    y.append(x[i])
    return y

cont = input("Bubble? (Y/N) ")
if cont == "Y":
    bubbling = True

while bubbling == True:
    previous = numbers
    numbers = bubble(numbers)

    if numbers == previous:
        end = input("The bubble sort has been finished" )
        bubbling = False
        break

    print(numbers)

    cont = input("Bubble? (Y/N) ")

    if cont == "Y":
        continue
    else:
        break

answered Mar 22, 2021 at 10:13

16dhudson 16dhudson

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