I need this list to append a list for each line in a file, then to sort the output. It takes input from a file (numbers.txt). I've tried everything I can think of to get it to sort; finally I've made some 'progress' but newlist2 here only returns none and newlist isn't sorted. What am I doing wrong?

import sys
import os


print("\n && ************************************************ &&\n && Welcome to the text document average calculator! && \n && ************************************************ &&\n\n Please ensure your file contains only numeric charactesr! \n By default, the program will look for a document named 'numbers' in this folder.")




def averager():
    
####Declarations     
    count = int(0)
    sunn = int(0)
    target = str('')
    beginbool = bool(False)
    
####Statement
    try:
        while beginbool == False:
            specify = input(" Specify directory? Y / N: ")
            if any(specify.lower() == f for f in ['y', 'Y', 'Yes', 'YES', 'YEs', 'yES', 'yEs', 'yeS']):
                rngfile = open(input('Please input file location: '), 'r')
                beginbool == True
                break
            elif any(specify.lower() == f for f in ['N', 'n', 'No', 'no', 'nO', 'NO']):
                rngfile = open("numbers.txt", 'r')
                beginbool == True
                break
            else:
                print('Please input yes, no, or something close at least...')
                pass
            
####User Data
        print('\n&&***********************************&&')
        print("&& Line:        LiVal:        Sum:   &&\n&&***********************************&&")

####For loop
        for line in rngfile:
            iteration = int(line)
            truelist = list([])
            truelist.append(int(iteration))
            count  = 1
            sunn  = iteration
            if sunn == 0 and count == 0:
                print("Empty list detected.")
            elif sunn != 0 and count != 0:
                newlist = [int(x) for x in truelist]
                newlist.sort(key=int, reverse=True)
                newlist2 = newlist.sort(key=int, reverse=True)
                print(sorted(newlist))
                print(newlist2)
                pass
            else:
                pass
            

####Close
        rngfile.close()

####Exceptions

    except IOError:
        print("Error reading the file.")
    except ZeroDivisionError:
        print("Divided by zero? (This usually happens when the filename is incorrect, or the file is empty.)")

        
####Display Average
    average = (sunn / count)



####User Data
    print('&&***********************************&& \n\n The numerical average of the file is: ', average)
    print(' Thank you for using the numerical averager!')


    


####Run        
averager()

####Finish
input("\n Press any key to exit.") 
sys.exit(1)

CodePudding user response：

.sort() method is sorting list in-place, it always returns None

so in the line:

newlist2 = newlist.sort(key=int, reverse=True)

You are assign None to the newlist2 variable, consider using sorted function.

CodePudding user response：

You wrote

        for line in rngfile:
            ...
            truelist = list([])
            truelist.append(int(iteration))

That doesn't look right. You ensure it has zero lines, then you append a line.

Didn't you want to initialize truelist before starting the for loop?

You wrote

                newlist.sort(key=int, reverse=True)
                newlist2 = newlist.sort(key=int, reverse=True)

Again, that doesn't look right. The .sort() return value will always be None.

I recommend you avoid .sort(), and prefer sorted(). It is more modern and offers a far more convenient interface, handing back a new list each time. It supports the same options, e.g. key= and reverse=.