错误的正则表达式或奇怪的行为？

Question

Hello i post my question here because i don't understand my potential error. I am parsing ingredients'lists. Some of them have allegations in it such as '*no-ogm'. I succeed in extracting most of this allegations in a dictionary in order to extract directly from other ingredients lists allegation already referenced. Issue is that my regex works in all online regex tester but no in my jupyter notebook and i do not understand why. Here is an example:

string='''chickpeas* (31%), water, sesame oil* (11%), tofu* (soybeans*, water, gelling agent (nigari (magnesium chloride))), onions*, carrots*, yeast*, celery*, non-hydrogenated sunflower oil*, cashew nuts*, tomato paste*, vegetable bouillon* (sea salt, maize starch*, glucose syrup*, sunflower oil*, carrots*, onion*, parsnips*, turmeric*, ginger*, parsley*, nutmeg*, lovage*, bay leaves*, black pepper*), sea salt, ginger*, locust bean*, coriander*, turmeric*, cumin*, fenugreek*, nutmeg, black pepper*, cinnamon*, mustard seeds*, cardamom*, cayenne pepper* *from organic agriculture'''

and the regex:

pattern=re.findall('\*{1,3}\s{0,2}\bfrom organic agriculture\b\s{0,2}$',string)

In Regex101 and Pythex the subset of the string '*from organic agriculture' is clearly found. In my jupyter notebook pattern return 'None'... Why? i tried many regex flags to correct this behavior but... nothing worked.

This issue is particularly problematic at large scale because as i have a dictionary of allegations as mentioned above, i loop through each of my dictionary key to find corresponding patterns in multiple strings.

Thank you in advance for your help

Answer 1

You should use so-called raw-string here ie in place of:

pattern=re.findall('\*{1,3}\s{0,2}\bfrom organic agriculture\b\s{0,2}$',string)

do

pattern=re.findall(r'\*{1,3}\s{0,2}\bfrom organic agriculture\b\s{0,2}$',string)

This is crucial if you use regex class characters, like \\s .

Answer 2

在您的模式中b之前使用双反斜杠： '\\*{1,3}\\s{0,2}\\\\bfrom organic agriculture\\\\b\\s{0,2}$' （其他此类字符是换行符， \\ 。 ' 、 " 、 a 、 f 、 n 、 r 、 t 、 v 、 x ，后跟一个十六进制字符代码），或在模式前加上r ： r'\\*{1,3}\\s{0,2}\\bfrom organic agriculture\\b\\s{0,2}$' ，因此反斜杠不会被视为转义序列的开头 ( https://docs.python.org/2.0/ref/strings.html )。