如何在python中创建一个空的可变列表，以便以后可以添加列表项？

我想在python中创建一个空列表，以便以后可以通过函数向其中添加项。但当我试图通过函数向其中添加项时，它显示了“TypeError:无法隐式地将'tuple'对象转换为str”。为什么我会得到这个

page = "There are many variations of passages of Lorem Ipsum available, but the majority have suffered alteration in some form, by injected humour, " \
       "or randomised words which don't look even slightly believable. If you are going to use a passage of Lorem Ipsum, you need to be sure there isn't " \
       "anything embarrassing hidden in the middle of text. All the Lorem Ipsum generators on the Internet tend to repeat predefined chunks as necessary, " \
       "making this the first true generator on the Internet. It uses a dictionary of over 200 Latin words, combined with a handful of model sentence " \
       "structures, to generate Lorem Ipsum which looks reasonable. The generated Lorem Ipsum is therefore always free from repetition, injected humour, " \
       "or non-characteristic words etc."

find_word = "the"
word_positions = []
pos = 0

while page.find(find_word) != -1:
        word_positions.append(page.find((find_word, pos)))
        pos = pos + len(find_word)

print(word_positions)

---

在表达式

word\u positions.append（page.find（（find\u word，pos））

中，

page.find（（find\u word，pos））

将一个

元组传递给
page.find
，但是
page.find
期望第一个参数是字符串（要查找的单词）。你想要：

page.find(find_word, pos)

（注意，我删除了一组括号）


代码中还有其他一些逻辑错误。首先，您的循环可能会永远持续下去，因为
page.find（find\u word）
如果第一次找到某个内容，它将始终找到该内容。将其更改为：

while page.find(find_word, pos) != -1:

其次，您的列表中会出现以下重复项：

pos = pos + len(find_word)

找到的单词数量与您希望在哪个位置找到它们无关。您可能想要：

pos = word_positions[-1] + 1

因为您希望在最后找到的项目之后立即继续查找


最后，使用
re
几乎可以轻松完成此任务。（您甚至不必编写正则表达式，因为您需要的是文字！）：

请注意，这也可以写在一行中作为列表：

word_positions = [m.start() for m in re.finditer(find_word, page)]

那么：

import re

page = "There are many variations of passages of Lorem Ipsum available, but the majority have suffered alteration in some form, by injected humour, " \
       "or randomised words which don't look even slightly believable. If you are going to use a passage of Lorem Ipsum, you need to be sure there isn't " \
       "anything embarrassing hidden in the middle of text. All the Lorem Ipsum generators on the Internet tend to repeat predefined chunks as necessary, " \
       "making this the first true generator on the Internet. It uses a dictionary of over 200 Latin words, combined with a handful of model sentence " \
       "structures, to generate Lorem Ipsum which looks reasonable. The generated Lorem Ipsum is therefore always free from repetition, injected humour, " \
       "or non-characteristic words etc."

find_word = "the"
word_positions = []
pos = 0

for match in re.finditer(find_word, page):
    word_positions.append( (find_word, match.start()) )

print(word_positions)

它输出：

[('the', 68), ('the', 273), ('the', 317), ('the', 341), ('the', 371), ('the', 443), ('the', 471), ('the', 662)]

page.find（（find_-word，pos））
您之所以得到这个结果，是因为您将一个元组传递给了
find
。我删除了一组括号。但它并没有将单词的位置添加到列表中（单词的位置）
[('the', 68), ('the', 273), ('the', 317), ('the', 341), ('the', 371), ('the', 443), ('the', 471), ('the', 662)]