在正则表达式（python）中为一个字符串段获取太多匹配项
[英]Getting too many matches for one string segment in regex (python)
问题描述
I'm trying to write a regex script for finding all instances of money in a text, and my code works correctly but I can't figure out why it's finding multiple versions of things in my strings.
我正在尝试编写一个正则表达式脚本来查找文本中的所有金钱实例，并且我的代码可以正常工作，但我无法弄清楚为什么它会在我的字符串中找到多个版本的东西。
For example, in this code:例如，在这段代码中：
string = "$50.00"
print "number dollars: "
print re.findall("\-?\(?\$?\s*\-?\s*\(?(((\d{1,3}((\,\d{3})*|\d*))?(\.\d{1,4})?)|((\d{1,3}((\,\d{3})*|\d*))(\.\d{0,4})?))\)?\ ?(one)?\ ?(two)?\ ?(three)?\ ?(four)?\ ?(five)?\ ?(six)?\ ?(seven)?\ ?(eight)?\ ?(nine)?\ ?(ten)?\ ?(eleven)?\ ?(twelve)?\ ?(thirteen)?\ ?(fourteen)?\ ?(fifteen)?\ ?(sixteen)?\ ?(seventeen)?\ ?(eighteen)?\ ?(nineteen)?\ ?(hundred)?\ ?(thousand)?\ ?(million)?\ ?(billion)?\ ?(trillion)?\ ?(dollars)?\ ?(pounds)?\ ?(euros)?", string)
This is the result I get:这是我得到的结果：
number dollars:
[('50.00', '50.00', '50', '', '', '.00', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', ''), ('', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '')]
this is the regex by itself:这本身就是正则表达式：
\-?\(?\$?\s*\-?\s*\(?(((\d{1,3}((\,\d{3})*|\d*))?(\.\d{1,4})?)|((\d{1,3}((\,\d{3})*|\d*))(\.\d{0,4})?))\)?\ ?(one)?\ ?(two)?\ ?(three)?\ ?(four)?\ ?(five)?\ ?(six)?\ ?(seven)?\ ?(eight)?\ ?(nine)?\ ?(ten)?\ ?(eleven)?\ ?(twelve)?\ ?(thirteen)?\ ?(fourteen)?\ ?(fifteen)?\ ?(sixteen)?\ ?(seventeen)?\ ?(eighteen)?\ ?(nineteen)?\ ?(hundred)?\ ?(thousand)?\ ?(million)?\ ?(billion)?\ ?(trillion)?\ ?(dollars)?\ ?(pounds)?\ ?(euros)?
1 个解决方案
解决方案1
0
The results contain a string from each and every parenthesized group , corresponding to the portion of the string matched by the subexpression in each group, in order of opening parentheses (eg (\d+(\.\d+)?) would give ['50.00', '.00'] ).结果包含来自每个带括号的 group的字符串，对应于每个组中的子表达式匹配的字符串部分，按照左括号的顺序（例如(\d+(\.\d+)?)将给出['50.00', '.00'] ）。 To prevent the contents of a group from being captured, prefix the subexpression with a ?: (eg (?:,\d{3})*|\d*) );为防止组的内容被捕获，请在子表达式前加上?:前缀（例如(?:,\d{3})*|\d*) ）； this creates a non-capturing group .这将创建一个非捕获组。
The majority of the groups are for words that don't appear in the string, which produces most of empty strings in the result.大多数组用于未出现在字符串中的单词，这会在结果中产生大部分空字符串。
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