在python中的while循环中返回循环

Question

I'm trying to make a function that returns this:

42334
44423
21142
14221

From this:

polje = [[1, 2, 4, 4], [4, 1, 4, 2], [2, 1, 4, 3], [2, 4, 2, 3], [1, 2, 3, 4]]

The function just goes through the lists and prints their elements starting with the last ones. I've been able to get the right result by printing, but i'm trying to make it so that the function simply returns the result. How do i do it? I've tried generators, single line for loops etc. but notes on the internet are not plentiful and are often writen in a complicated way...

Here's the code i've got so far:

def izpisi(polje):
    i = len(polje[0]) - 1
    while i >= 0:
        for e in polje:
            print(e[i], end="")
        i -= 1
        print("\n")
    return 0

Answer 1

>>> polje = [[1, 2, 4, 4], [4, 1, 4, 2], [2, 1, 4, 3], [2, 4, 2, 3], [1, 2, 3, 4]]
>>> def izpisi(polje):
        return zip(*map(reversed, polje))

>>> for line in izpisi(polje):
        print(*line, sep='')


42334
44423
21142
14221

zip(*x) transposes a matrix. However you start at the last column so I simply add map(reversed,) to handle that.

The rest is just printing each line.

Answer 2

you can change your code to store the items in a list instead of print them. and store each list in another list in order to return all of them.

like this:

def izpisi(polje):
    a = []
    i = len(polje[0]) - 1
    while i >= 0:
        l = []
        for e in polje:
            l.append(e[i])
        i -= 1
        a.append(l)
    return a

Answer 3

def izpisi(polje):
    return '\n'.join([ # inserts '\n' between the lines
        ''.join(map(str, sublst)) # converts list to string of numbers
        for sublst in zip(*polje) # zip(*...) transposes your matrix
    ][::-1]) # [::-1] reverses the list

polje = [[1, 2, 4, 4], [4, 1, 4, 2], [2, 1, 4, 3], [2, 4, 2, 3], [1, 2, 3, 4]]
print izpisi(polje)