查找可能后跟小数点的所有数字

Question

I am trying to findall combinations of of a digit followed by decimal point and another digit. The last final decimal point may be missing

E.g., 
1.3.3 --> Here there are two combinations 1.3 and 3.3
1.3.3. --> Here there are two combinations 1.3 and 3.3

However, when I run the following code?

st='1.2.3 The Mismatch of Accommodation and Disparity and the Depths of Focus and of Field'
import re
re.findall('\d\.\d+',st)
['1.2']

What am I doing wrong?

Answer 1

因为您无法将相同的字符匹配两次，所以您需要将一个捕获组放在一个先行断言中，以便不消耗该点右侧的数字：

re.findall(r'(?=(\d+\.\d+))\d+\.', st)

Answer 2

You may match 1+ digits in the consuming pattern and capture the fractional part inside a positive lookahead, then join the groups:

import re
st='1.2.3 The Mismatch of Accommodation and Disparity and the Depths of Focus and of Field'
print(["{}{}".format(x,y) for x,y in re.findall(r'(\d+)(?=(\.\d+))',st)])

See the Python demo and a regex demo .

Regex details :

• (\\d+) - Group 1: one or more digits
• (?=(\\.\\d+)) - a positive lookahead that requires the presence of:
  • (\\.\\d+) - Group 2: a dot and then 1+ digits