Python 程序在不应该打印时打印 None

Question

I wrote a program that outputs the longest sequence of equal numbers when I press 2 in the console, but for some reason it prints the numbers tied to each other (ie if I input 1 2 2 2 4 5 it outputs 222 instead of 2 2 2) and for some reason it also prints None

The assertion tests that I made also fail for some reason

Input: press 1, input 1 2 2 2 2 4 5 6 1 4

Expected output: press 2, then it should show 2 2 2 2 2

Actual output: 22222 None

def lista_egale(lst1):
    l = 1
    prev_one = None
    number = 0
    lmax = -1
    for current in lst1:
        if prev_one == current:
            l += 1
        elif l > lmax:
            lmax = l
            number = prev_one
            l = 1
        prev_one = current
    print(number * lmax)

def test_egale():
    assert lista_egale([1, 2, 2, 2, 4, 5, 6]) == 2 2 2
    assert lista_egale([4, 1, 2, 4, 1, 2, 3, 2]) == 1
    assert lista_egale([1, 1, 1, 1, 1, 2, 2, 2, 2]) == 1 1 1 1 1

def show_menu():
    print("lists")
    print("1. Enter the list")
    print("2. Check if the list has a max sequence of equal numbers and print it")
    print("4. exit")


def ui_read_list():
     input_list = input("Numbers go here ")
     return input_list.split()

def run():
    global lst1
    lst1 = []
    show_menu()
    while True:
        cmd = input(">>>")
        if cmd == "4":
            return
        if cmd == "1":
            lst1 = ui_read_list()
        elif cmd == "2":
            print(lista_egale(lst1))
        else:
            print("invalid command")

def main():
    run()
    test_egale()
    #test_munte()

main()

Answer 1

you run

print(lista_egale(lst1))

The return value of your function

lista_egale(lst1)

is None , which gets printed. Probably you want to run simply:

lista_egale(lst1)

Answer 2

This worked for me except for the second assertion which (to me) doesn't make sense at all. Why would you want [1] to be returned and not anything else? Anyway, it returns [4] in that case.

def lista_egale(lst1):
    l = 0
    prev_one = None
    number = 0
    lmax = -1
    for current in lst1:
        if prev_one == current:
            l += 1
        elif l > lmax:
            lmax = l
            number = prev_one
            l = 1
        prev_one = current
    return ([number] * lmax)

def test_egale():
    assert lista_egale([1, 2, 2, 2, 4, 5, 6]) == [2, 2, 2]
    assert lista_egale([4, 1, 2, 4, 1, 2, 3, 2]) == [1]
    assert lista_egale([1, 1, 1, 1, 1, 2, 2, 2, 2]) == [1, 1, 1, 1, 1]

def show_menu():
    print("lists")
    print("1. Enter the list")
    print("2. Check if the list has a max sequence of equal numbers and print it")
    print("4. exit")


def ui_read_list():
    input_list = input("Numbers go here ")
    return input_list.split()

def run():
    global lst1
    lst1 = []
    show_menu()
    while True:
        cmd = input(">>>")
        if cmd == "4":
            return
        if cmd == "1":
            lst1 = ui_read_list()
        elif cmd == "2":
            print(lista_egale(lst1))
        else:
            print("invalid command")

def main():
    run()
    test_egale()
    #test_munte()

main()

EDIT:

Your mistakes were:

1. l was initialized as 1 even though it should've been initialized to 0 (because if the longest "streak" is 1-long, nothing would reach the l>lmax .
2. In the lista_eagle function you didn't return anything and instead printed the result.
3. You were printing number * lmax which is a number instead of the streak itself which you can get by concatenating the array to itiself lmax times (as shown here at return [number] * lmax ).

Answer 3

As others have pointed out, it sounds like you're expecting lista_egale to return a value rather than printing it. I think you also want to use the count function of lists to find how many times each item is in the list like this:

def lista_egale(lst1):
    lmax = -1
    number = 0
    for current in lst1:
        if lst1.count(current) > lmax:
            lmax = lst1.count(current)
            number = current
    return ' '.join([str(number)] * lmax)

Then to make your asserts work, the comparisons should also be strings like this:

def test_egale():
    assert lista_egale([1, 2, 2, 2, 4, 5, 6]) == '2 2 2'
    assert lista_egale([4, 1, 2, 4, 1, 2, 3, 2]) == '1'
    assert lista_egale([1, 1, 1, 1, 1, 2, 2, 2, 2]) == '1 1 1 1 1'

Answer 4

In lista_egale() 's print staement do this:

print((str(number)+" ")*lmax)

This will print 2 2 2 rather than 222