按条件从字符串中提取数字

Question

I want to extract digits from a short string, base on a condition that the digits is in front of a character ( S flag).

example and result:

> string = '10M26S'
> 26

> string = '18S8M10S'
> [18,10] OR 28

> string = '7S29M'
> 7

I can split the string to a list to get the individual element,

result = [''.join(g) for _, g in groupby('18S8M10S', str.isalpha)]
> ['18', 'S', '8', 'M', '10', 'S'] 

but how could I just get the 18 and 10 ?

Answer 1

Use re.findall with the regex r'(\\d+)S' . This matches all digits before a capital S .

>>> string = '10M26S'
>>> re.findall(r'(\d+)S',string)
['26']
>>> string = '18S8M10S'
>>> re.findall(r'(\d+)S',string)
['18', '10']
>>> string = '7S29M'
>>> re.findall(r'(\d+)S',string)
['7']

To get integer output, you can convert them in a list comp or use map

>>> list(map(int,['18', '10']))
[18, 10]

Answer 2

You could use a regular expression .

import re
regex = r"(\d+)S"
match = re.search(regex, '10M26S')
print(match.group(1))  # '26'

Answer 3

import re

[int(m) for m in re.findall(r'(\d+)S', "input10string30")]

this should do the trick