import re
pattern=r'\d\.\d+'  #限定符，\d 0-9数字出现1次或多次
s='I study python3.11 every day Python2.7 I love you' #待匹配字符串
s2='4.10python I study every day'
s3='python I study every day'
lst=re.findall(pattern,s)
lst2=re.findall(pattern,s2)
lst3=re.findall(pattern,s3)

print(lst)
print(lst2)
print(lst3)

（仅供参考）