在字符串列表的每个项目中查找特定模式（正则表达式）（Python）

Question

From this list problems= ["32 + 698", "3801 - 2", "45 + 43", "123 + 49"]

I want to get these numbers "\d*\s" that means 32,3801,45,123

Is there a way to look in each item of list and search there with a list comprehension?

I have only this attempt print([x for x in problems if re.search(r'\d*\s',x)]) , but it prints whole item if the "\d*\s" is there, so I get again ["32 + 698", "3801 - 2", "45 + 43", "123 + 49"]

(My aim is have a lenght of the longer number of each item, that would be 3,4,2,3)

Answer 1

You need to extract the first part before space in your strings. This can be done using group capturing. Here is the code you can use:

[re.search('(\d+)\s', x).group(1) for x in problems if re.search(r'(\d)*\s',x)]

Here (\d+)\s matches for one or more digits before a whitespace character and we extract the first group using the group(1) method.