从字符串列表中选择合适的选项答案

【问题标题】：selecting suitable options from list of strings从字符串列表中选择合适的选项
【发布时间】：2019-10-21 11:33:31
【问题描述】：

我有一个句子列表。例如：

x = ['Mary had a little lamb', 
           'Jack went up the hill', 
           'Jill followed suit',    
           'i woke up suddenly',
           'I just missed the train',
           'it was a really bad dream']

我想选择倒数第二个单词不是“the”的选项。我怎么能在 python 3 上做到这一点？我试过这个：

l = []
for i in x:
    for k in i: 
        if i.index(k) != (len(i) -2):
             l.append(' '.join(i))

我在小列表上工作，但不在大列表上（几千个元素）

【问题讨论】：

请展示您的尝试。
您的代码是如何“工作”的？它甚至没有"the"。将每个字符串的len(i)-1“间隔”副本添加到结果列表似乎是一种非常低效的方法。
它的部分代码，我也有一个不应该是倒数第二个单词的列表

标签： python python-3.x loops select

【解决方案1】：

您可以使用split 的列表推导将句子分成单词，然后使用索引[-2] 检查倒数第二个元素。

>>> [s for s in x if s.split()[-2] != "the"]
['Mary had a little lamb',
 'Jill followed suit',
 'i woke up suddenly',
 'it was a really bad dream']

【讨论】：

【解决方案2】：

您可以使用filter() 方法并传递一个lambda，该lambda 将为没有"the" 作为倒数第二个字的字符串返回true：

x = ['Mary had a little lamb', 
           'Jack went up the hill', 
           'Jill followed suit',    
           'i woke up suddenly',
           'I just missed the train',
           'it was a really bad dream']

res = list(filter(lambda str : str.split()[-2] != "the", x)) 
print(res) # ['Mary had a little lamb', 'Jill followed suit', 'i woke up suddenly', 'it was a really bad dream']

【讨论】：

【解决方案3】：

x = ['Mary had a little lamb', 
           'Jack went up the hill', 
           'Jill followed suit',    
           'i woke up suddenly',
           'I just missed the train',
           'it was a really bad dream']

result = [y for y in x if y.split()[-2].lower() != 'the']

print(result)
# ['Jack went up the hill', 'I just missed the train']

【讨论】：

【解决方案4】：

x = ['Mary had a little lamb', 
           'Jack went up the hill', 
           'Jill followed suit',    
           'i woke up suddenly',
           'I just missed the train',
           'it was a really bad dream']

res =[sentence for sentence in x if 'the'!= sentence.split()[-2]]

print(res)

输出

['Mary had a little lamb', 'Jill followed suit', 'i woke up suddenly', 'it was a really bad dream']

【讨论】：

如果'the'不是倒数第二个？