使用索引python在字符串中插入引号

Question

我想在字符串（在文件input.txt中）的日期和文本周围插入引号（""）。这是我的输入文件：

created_at : October 9, article :   ISTANBUL — Turkey is playing a risky game of chicken in its negotiations with NATO partners who want it to join combat operations against the Islamic State group — and it’s blowing back with violence in Turkish cities. As the Islamic militants rampage through Kurdish-held Syrian territory on Turkey’s border, Turkey says it won’t join the fight unless the U.S.-led coalition also goes after the government of Syrian President Bashar Assad.
created_at : October 9, article :    President Obama chairs a special meeting of the U.N. Security Council last month. (Timothy A. Clary/AFP/Getty Images)  When it comes to President Obama’s domestic agenda and his maneuvers to (try to) get things done, I get it. I understand what he’s up to, what he’s trying to accomplish, his ultimate endgame. But when it comes to his foreign policy, I have to admit to sometimes thinking “whut?” and agreeing with my colleague Ed Rogers’s assessment on the spate of books criticizing Obama’s foreign policy stewardship.

我想在日期和文本周围加上引号，如下所示：

created_at : "October 9", article :   "ISTANBUL — Turkey is playing a risky game of chicken in its negotiations with NATO partners who want it to join combat operations against the Islamic State group — and it’s blowing back with violence in Turkish cities. As the Islamic militants rampage through Kurdish-held Syrian territory on Turkey’s border, Turkey says it won’t join the fight unless the U.S.-led coalition also goes after the government of Syrian President Bashar Assad".
created_at : "October 9", article :    "President Obama chairs a special meeting of the U.N. Security Council last month. (Timothy A. Clary/AFP/Getty Images)  When it comes to President Obama’s domestic agenda and his maneuvers to (try to) get things done, I get it. I understand what he’s up to, what he’s trying to accomplish, his ultimate endgame. But when it comes to his foreign policy, I have to admit to sometimes thinking “whut?” and agreeing with my colleague Ed Rogers’s assessment on the spate of books criticizing Obama’s foreign policy stewardship".

下面是我的代码，它查找逗号的索引（,在日期之后）和文章的索引，然后通过使用它们，我想在日期周围插入引号。我也想在文本周围插入引号，但如何做到这一点？你知道吗

f = open("input.txt", "r")
for line in f:
    article_pos = line.find("article")
    print article_pos
    comma_pos = line.find(",")
    print comma_pos

Answer 1

您还可以查看regex库re。 例如

>>> import re
>>> print(re.sub(r'created_at:\s(.*), article:\s(.*)',
...              r'created_at: "\1", article: "\2"',
...              'created_at: October 9, article: ...'))
created_at: "October 9", article: "..."

re.sub的第一个参数是您试图匹配的模式。paren ()捕获匹配项，并可与\1一起用于第二个参数。第三个参数是文本行。你知道吗

Answer 2

虽然您可以通过find和切片之类的低级操作来实现这一点，但这并不是简单或惯用的方法。你知道吗

首先，我将向您展示如何按照您的方式进行：

comma_pos = line.find(", ")
first_colon_pos = line.find(" : ")
second_colon_pos = line.find(" : ", comma_pos)
line = (line[:first_colon_pos+3] + 
        '"' + line[first_colon_pos+3:comma_pos] + '"' +
        line[comma_pos:second_colon_pos+3] +
        '"' + line[second_colon_pos+3:] + '"')

但是你可以更容易地把线路分成几部分，咀嚼这些部分，然后把它们重新连接起来：

dateline, article = line.split(', ', 1)
key, value = dateline.split(' : ')
dateline = '{} : "{}"'.format(key, value)
key, value = article.split(' : ')
article = '{} : "{}"'.format(key, value)
line = '{}, {}'.format(dateline, article)

然后你可以把重复的部分重构成一个简单的函数，这样你就不需要写两次同样的东西（如果你以后需要写四次的话，这可能会很有用）。你知道吗

使用正则表达式更容易，但对于新手来说，这可能没有那么容易理解：

line = re.sub(r'(.*?:\s*)(.*?)(\s*,.*?:\s*)(.*)', r'\1"\2"\3"\4"', line)

它的工作原理是捕获一个组中第一个:（及其后的任何空格）之前的所有内容，然后捕获第二个组中从那里到第一个逗号的所有内容，依此类推：

(.*?:\s*)(.*?)(\s*,.*?:\s*)(.*)

Debuggex Demo

注意，regex的优点是我可以非常简单地说“后面的任何空格”，而使用find或split时，我必须明确指定冒号两边正好有一个空格，逗号后面正好有一个空格，因为如果没有\s*这样的表达方式，搜索“0或更多空格”会困难得多。你知道吗