无法弄清楚如何在此Python代码中重新分配列表中的元素

我理解如何访问列表列表中的元素通常是有效的.我知道如果你有一个列表L = [[‘a’,’b’],[‘c’,d’],[‘e’,’f’]],你可以用L [来访问’a’ 0] [0].不过,我不确定为什么同样的事情不适用于以下战舰游戏代码：

from random import randint
from random import choice

# make a 5x5 board
board = []
row = ['O']*5
for x in range(5):
    board.append(row)

def print_board():
    for item in board:
        print ' '.join(item)

#check if input falls within 5x5 grid
def check_valid(guess_row,guess_column):
    return guess_row in range(5) and guess_column in range(5)
#return True- is valid choice,return False- not valid choice

#check that the input hasn't been guessed previously
def check_repeat(guess_row,guess_column):
    return board[guess_row][guess_column] != 'O'
#return True- repeat,reurn False- new

#check if input is a correct answer
def check_correct(guess_row,guess_column):
    return (guess_row,guess_column) == (row1,col1) or (guess_row,guess_column) == (row2,col2)
#return True- is correct,return False- is not correct

#place a 2-position ship
while True:
    #pick random place to start
    row1 = randint(0,4)
    col1 = randint(0,4)
    #choose adjacent second position
    move_direction = choice(['north','south','east','west'])
    if move_direction == 'north':
        row2 = row1 - 1
        col2 = col1
    elif move_direction == 'south':
        row2 = row1 + 1
        col2 = col1
    elif move_direction == 'east':
        row2 = row1
        col2 = col1 + 1
    else: # must be west 
        row2 = row1
        col2 = col1 - 1
    #check that the second position is valid,else pick new values
    if row2 in range(5) and col2 in range(5):
        break
positions_left = 2 #how many points player needs to hit
#you now have a ship at coordinates (row1,col1),(row2,col2)

turns = 5

#the gameflow itself:
print 'let's play battleship!'
while turns > 0:
    print 'You have %i turns remaining.' % turns
    print_board()
    guess_row = int(raw_input('Guess a row: ')) - 1 #-1 to account for python 0-indexing
    guess_column = int(raw_input('Guess a column: ')) - 1

    if check_valid(guess_row,guess_column) == False:
        print 'Sorry,those aren't valid coordinates'
    else: #continue game if valid
        turns -= 1
        if check_repeat(guess_row,guess_column): #old guess
            print 'You seem to have guessed that already.'
            turns += 1 #don't count this turn
        elif check_correct(guess_row,guess_column):
            print 'Hit!'
            board[guess_row][guess_column] = '!'
            positions_left -= 1
            if positions_left == 0:
                'You sunk the battleship!'
                turns = 0 #stops game
            else:
                print 'You can sink this ship in %i more hits!' % positions_left
        else:
            board[guess_row][guess_column] = 'X'
            print 'Sorry,you missed!'

问题发生在评估玩家猜测之后,我尝试将’O’重新分配给’！’ (表示命中)或’X'(表示未命中).这应该发生在：

  elif check_correct(guess_row,guess_column):
                print 'Hit!'
                board[guess_row][guess_column] = '!'

在：

    else:
        board[guess_row][guess_column] = 'X'
        print 'Sorry,you missed!'

相反,会发生什么是整个列最终被重新分配给该值.因此,当玩家猜测第1行第1列时,该猜测被解释为guess_row = 0,guess_column = 0.
我希望董事会的新价值变成：

[['X','O','O'],['O','O']]

相反,它变成：

[['X',['X','O']]

这真是奇怪,因为当我拿出代码的小片段并尝试做这件事时,它工作正常,但是当我尝试将其作为整个代码的一部分时,我看不到我所缺少的东西. 最佳答案 问题是您在每次迭代时将相同的行变量添加到您的电路板中.您应该添加一个新行,如下所示：

board = []
for _ in range(5):
    board.append(['O'] * 5)

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