Python在找到字符串的第一个实例后从字符串中提取n个句子

Question

我想提取在列表“单词”中找到元素的第一个实例。我下面的代码正确地做到了这一点。 但是对于列表“单词”中的某些项目（例如狗和猫），我想提取字符串的第一次出现，以及之后的 3 个句子 - 请有人能告诉我如何做到这一点吗？

我的代码如下：

text= 'the dog was there. the cat is there too. python is the best. she has a kitten. cat is cute. the dog want want want was there. my dog is a puppy. chocolate brownies. flower power.'

words=['dog', 'chocolate', 'cat' ,'flower']
lst=[]

for j in words:
    for i in text.split('.'):
        if j in i:
            lst.append (i.split('.')[0]) 
            break
else:
    None
     
print(lst)

期望的输出：

['the dog was there. the cat is there too. python is the best' , 'chocolate brownies', 'the cat is there too. python is the best. she has a kitten', 'flower power']

我尝试过的（索引） - 不确定我做错了什么

if j[0] in i:
 lst.append( i.split('.')[0:3]
if j[2] in i:
 lst.append. i.split('.')[0:3]

谢谢

Answer 1

为了提取第一个实例，您的代码确实有效，但有一些不必要的代码。

只需附加i，而不是i.split('.')[0]。您的i 已被拆分。

for j in words:
    for i in text.split('.'):
        if j in i:
            lst.append(i) 
            break

现在提取n个句子，

for j in words:
    for index, i in enumerate(text.split('.')):
        if j in i:
            if j == "dog" or j == "cat":
               lst.append('.'.join(text.split('.')[index:index+n]))
            else:
               lst.append(i) 
            break

这里使用枚举，我们跟踪句子的索引。如果我们遇到一个带有狗或猫的句子，而不是追加我们添加长度为 n 的子列表。

Answer 2

任务1：拆分段落，得到句子列表。对于列表词中的每个查询词，检查它是否存在于句子列表中，如果存在则将其添加到结果中。

text= 'the dog was there. the cat is there too. python is the best. she has a kitten. cat is cute. the dog want want want was there. my dog is a puppy. chocolate brownies. flower power.'

words=['dog', 'chocolate', 'cat' ,'flower']

lst=[]

list_sentences = text.split('.')

for query_word in words:
    for sentence in list_sentences:
        if query_word in sentence:
            lst.append (sentence) 
            break
else:
    None
     
print(lst)

重要提示：你的代码可以工作，但它是错误的，因为你有一个句子 i，所以你直接附加它，在你的代码中你托盘拆分它 lst.append(i.split('.')[0]) 并且因为句子i 不包含 '。'，你最后得到的结果是一样的。

任务 2：当您附加所有三个句子时，这是您的第二个任务。完全相同的代码，只需添加从找到查询词的句子开始的所有三个句子。我们使用 enumerate 来跟踪索引。

text= 'the dog was there. the cat is there too. python is the best. she has a kitten. cat is cute. the dog want want want was there. my dog is a puppy. chocolate brownies. flower power.'

words=['dog', 'chocolate', 'cat' ,'flower']

list_sentences = text.split('.')

list_task2 = []
query_word = words[0] # just example, you can change it

for i, sentence in enumerate(list_sentences):
        if query_word in sentence:
            #list_task2.append (list_sentences[i:i+3])
            list_task2 = list_task2 + list_sentences[i:i+3]
            break
print(list_task2)