下面提到的语法是什么意思？

Question

我正在用Python3.7编写著名的hamlet机器人程序。因此，我有一个来自莎士比亚著名哈姆雷特戏剧的部分脚本(以字符串输入的形式)。

我的任务是将脚本中的句子分成列表，然后进一步创建句子中单词的列表。

我正在使用从互联网上复制的以下代码：

“”“

### BEGIN SOLUTION
def hamsplits__soln0():
    cleanham = ""
    for char in hamlet_text:
        swaplist = ["?","!", "."] #define the puntuations which we need to replace.
        if char in swaplist:
            cleanham += "." #replace all the puntuations with .
        elif char is " ":
            cleanham += char #convert all the spaces to character type.
        elif char.isalpha():
            cleanham += char.lower() #bringing all the letters in lower case.

    hamlist = cleanham.split(". ") #spliting all the sentences as the parts of a list.

    for sentence in hamlist:
        hamsplits.append(sentence.split()) #spliting all the words of the sentences as the part of list.

    if hamsplits[-1][-1][-1] == '.':
        hamsplits[-1][-1] = hamsplits[-1][-1][:-1] # Remove trailing punctuation 

“”“

在这里，我想要理解代码最后两行的含义。

if hamsplits[-1][-1][-1] == '.':
        hamsplits[-1][-1] = hamsplits[-1][-1][:-1] # Remove trailing punctuation 

如果有人能帮我的话？

Answer 1

让我们假设hamsplits是一个3D数组。

第一行检查最后一条平面的最后一行中的最后一个元素是否为点，然后从最后一行中删除最后一个元素

>>> x = [1, 2, 3]
>>> x = x[:-1] # Remove last element
>>> x
[1, 2]

应该具有与

del hamsplits[-1][-1][-1]

Answer 2

让我们举个例子，假设我们有如下的腿裂

hamsplits=['test',['test1',['test2','.']]]
print(hamsplits[-1][-1][-1])  # it would be equal to '.' 
if hamsplits[-1][-1][-1] == '.':  # here we are comparing it with "."
       hamsplits[-1][-1] = hamsplits[-1][-1][:-1] # in this we are just removing the '.' from third list in hamsplits and taking all remaining elements
print(hamsplits[-1][-1][:-1]) # it would print ['test2'] (removing last element from list) and overwriting in hamsplits[-1][-1]

**Note**:
hamsplits[:-1] is removing the last element, it's a slicing in python
hamsplits[-1] you are accessing the last element

希望这能有所帮助！