Python 正则表达式：只获取一个匹配的表达式

Question

所以我正在努力解决一个将多个正则表达式与一个语句匹配的程序：

import re

line = "Remind me to pick coffee up at Autostrada at 4:00 PM"

matchObj = re.match( r'Remind me to (.*) at (.*?) at (.*?) .*', line, re.M|re.I|re.M)
matchObj2 = re.match( r'Remind me to (.*) at (.*?) .*', line, re.M|re.I)

if matchObj:
   print("matchObj.group() : ", matchObj.group())
   print("matchObj.group(1) : ", matchObj.group(1))
   print("matchObj.group(2) : ", matchObj.group(2))
   print("matchObj.group(3) :", matchObj.group(3))
else:
   print("No match!!")
if matchObj2:
   print("matchObj2.group() : ", matchObj2.group())
   print("matchObj2.group(1) : ", matchObj2.group(1))
   print("matchObj2.group(2) : ", matchObj2.group(2))
else:
   print("No match!!")

现在，我希望一次只匹配一个正则表达式，如下所示：

matchObj.group() :  Remind me to pick coffee up at Autostrada at 4:00 PM
matchObj.group(1) :  pick coffee up
matchObj.group(2) :  Autostrada
matchObj.group(3) : 4:00

相反，两个正则表达式都与语句匹配，如下所示：

matchObj.group() :  Remind me to pick coffee up at Autostrada at 4:00 PM
matchObj.group(1) :  pick coffee up
matchObj.group(2) :  Autostrada
matchObj.group(3) : 4:00
matchObj2.group() :  Remind me to pick coffee up at Autostrada at 4:00 PM
matchObj2.group(1) :  pick coffee up at Autostrada
matchObj2.group(2) :  4:00

这里只有 matchObj 应该是正确的匹配项，那么如何阻止其他正则表达式报告匹配项？

Answer 1

问题是每个匹配第一个正则表达式的字符串也匹配第二个（任何匹配at (.*?) .* 也匹配.*。所以matchObj2 是 实际上是正确的匹配。

如果你想区分这两种情况，当且仅当第一个不匹配时，你需要应用第二个正则表达式。

import re

line = "Remind me to pick coffee up at Autostrada at 4:00 PM"

matchObj = re.match( r'Remind me to (.*) at (.*?) at (.*?) .*', line, re.M|re.I|re.M)
matchObj2 = re.match( r'Remind me to (.*) at (.*?) .*', line, re.M|re.I)

if matchObj:
   print("matchObj.group() : ", matchObj.group())
   print("matchObj.group(1) : ", matchObj.group(1))
   print("matchObj.group(2) : ", matchObj.group(2))
   print("matchObj.group(3) :", matchObj.group(3))
elif matchObj2:
   print("matchObj2.group() : ", matchObj2.group())
   print("matchObj2.group(1) : ", matchObj2.group(1))
   print("matchObj2.group(2) : ", matchObj2.group(2))
else:
   print("No match!!")