Python 整数和整数的正则表达式？
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Regular Expression for whole numbers and integers?
提问by Sahil Thapar
I am trying to detect all integers and whole numbers (among a lot of other things) from a string. Here are the regular expressions I am currently using:
我正在尝试从字符串中检测所有整数和整数（以及许多其他内容）。以下是我目前使用的正则表达式：
Whole numbers: r"[0-9]+"
整数： r"[0-9]+"
Integers: r"[+,-]?[0-9]+"
整数： r"[+,-]?[0-9]+"
Here are the issues:
以下是问题：
- The whole numbers regex is detecting negative numbers as well, which I cannot have. How do I solve this? If I use a space before at start of the regex I get only positive numbers, but then I get a space at the start of my output!
- For whole numbers, I would like to detect positive numbers with the format
+[0-9]but store them without the sign. - For integers, I would like to store any positive integer detected with the sign, irrespective if it is present in the original string.
- 整数正则表达式也在检测负数，这是我不能拥有的。我该如何解决这个问题？如果我在正则表达式开始前使用空格，我只会得到正数，但随后我会在输出开始时得到一个空格！
- 对于整数，我想检测具有格式的正数，
+[0-9]但不带符号存储它们。 - 对于整数，我想存储任何用符号检测到的正整数，无论它是否存在于原始字符串中。
Almost done now: One last thing, I have a string that says "Add 10 and -15". I want to store the integers in a list. I do so using the findall(). While storing the numbers is it possible to store '10' as '+10'
现在差不多完成了：最后一件事，我有一个字符串，上面写着“加 10 和 -15”。我想将整数存储在列表中。我使用 findall() 这样做。存储数字时，可以将“10”存储为“+10”
采纳答案by Tim Pietzcker
For positive integers, use
对于正整数，使用
r"(?<![-.])\b[0-9]+\b(?!\.[0-9])"
Explanation:
解释：
(?<![-.]) # Assert that the previous character isn't a minus sign or a dot.
\b # Anchor the match to the start of a number.
[0-9]+ # Match a number.
\b # Anchor the match to the end of the number.
(?!\.[0-9]) # Assert that no decimal part follows.
For signed/unsigned integers, use
对于有符号/无符号整数，请使用
r"[+-]?(?<!\.)\b[0-9]+\b(?!\.[0-9])"
The word boundaries \bare crucial to make sure that the entire number is matched.
单词边界\b对于确保整个数字匹配至关重要。
回答by Inbar Rose
You almost had it.
你几乎拥有它。
import re
regex = re.compile(r'(\d+)|([\+-]?\d+)')
s = "1 2 3 4 5 6 +1 +2 +3 -1 -2 -3 +654 -789 321"
for r in regex.findall(s):
if r[0]:
# whole (unsigned)
print 'whole', r[0]
elif r[1]:
# a signed integer
print 'signed', r[1]
Results:
结果：
>>>
whole 1
whole 2
whole 3
whole 4
whole 5
whole 6
signed +1
signed +2
signed +3
signed -1
signed -2
signed -3
signed +654
signed -789
whole 321
Or, you could use "or" to get the actual result in a "nicer" way:
或者，您可以使用“或”以“更好”的方式获得实际结果：
print [r[0] or r[1] for r in regex.findall(s)]
>>>
['1', '2', '3', '4', '5', '6', '+1', '+2', '+3', '-1', '-2', '-3', '+654', '-789', '321']
Edit: As per your question " is it possible to store '10' as '+10'" :
编辑：根据您的问题“是否可以将 '10' 存储为 '+10'”：
import re
def _sign(num):
if r[0]:
return '+%s'%r[0]
else:
return r[1]
regex = re.compile(r'(\d+)|([\+-]?\d+)')
s = "1 2 3 4 5 6 +1 +2 +3 -1 -2 -3 +654 -789 321"
print [_sign(r) for r in regex.findall(s)]
>>>
['+1', '+2', '+3', '+4', '+5', '+6', '+1', '+2', '+3', '-1', '-2', '-3', '+654', '-789', '+321']
Or in 1-line:
或在 1 行中：
print ['+%s'%r[0] if r[0] else r[1] for r in regex.findall(s)]
>>>
['+1', '+2', '+3', '+4', '+5', '+6', '+1', '+2', '+3', '-1', '-2', '-3', '+654', '-789', '+321']
