为什么我的Python正则表达式与Windows中的换行符\r\n不匹配？

Question

我对Python还是相当陌生的，我的一个正则表达式遇到了问题。我在网上对此进行了研究，并用Python尝试了很多东西，但我还是被卡住了。因为我使用的是Windows，所以我希望\r\n在文本文件中匹配一个新的换行符，因为在Windows中，行是这样终止的。但我发现只有\n个匹配项。为什么呢

这是我的代码（使用\r\n，不匹配）

filename = 'C:\\Users\\jason\\OneDrive\\Documents\\LTspice_my_work\\example_ac_analysis_2.raw'
with open (filename, 'r' ) as f:
    content = f.read()
    print(content)
    pattern3 = r'Variables:\r\n(.*)Values:' 
    print("Here's what matches:")
    text = re.search( pattern3,content,re.DOTALL).group(1)
    print(text)

返回：

Command: Linear Technology Corporation LTspice XVII
Variables:
        0       frequency       frequency
        1       V(v1)   voltage
        2       V(vout) voltage
        3       I(C1)   device_current
        4       I(R1)   device_current
        5       I(V1)   device_current
Values:
0               1.000000000000000e+000,0.000000000000000e+000
        2.000000000000000e+000,0.000000000000000e+000
        1.998028025380720e+000,-6.276990166202591e-002
        3.943949238559487e-007,1.255398033240518e-005
        -3.943949238559341e-007,-1.255398033240518e-005
        -3.943949238559568e-007,-1.255398033240518e-005
1               3.162277660168380e+000,0.000000000000000e+000
        2.000000000000000e+000,0.000000000000000e+000
        1.980453705393099e+000,-1.967499214255068e-001
        3.909258921380289e-006,3.934998428510137e-005
        -3.909258921380277e-006,-3.934998428510137e-005
        -3.909258921380287e-006,-3.934998428510137e-005


Here's what matches:
Traceback (most recent call last):

  File "C:\Users\jason\OneDrive\Documents\Python\Python_scripts\example_ltspice_pytool.py", line 176, in <module>
    text = re.search( pattern3,content,re.DOTALL).group(1)

AttributeError: 'NoneType' object has no attribute 'group'

但是，当我仅使用\n时，我得到了与此代码匹配的代码

filename = 'C:\\Users\\jason\\OneDrive\\Documents\\LTspice_my_work\\example_ac_analysis_2.raw'
with open (filename, 'r' ) as f:
    content = f.read()
    print(content)
    pattern3 = r'Variables:\n(.*)Values:' 
    print("Here's what matches:")
    text = re.search( pattern3,content,re.DOTALL).group(1)
    print(text)

返回

Command: Linear Technology Corporation LTspice XVII
Variables:
        0       frequency       frequency
        1       V(v1)   voltage
        2       V(vout) voltage
        3       I(C1)   device_current
        4       I(R1)   device_current
        5       I(V1)   device_current
Values:
0               1.000000000000000e+000,0.000000000000000e+000
        2.000000000000000e+000,0.000000000000000e+000
        1.998028025380720e+000,-6.276990166202591e-002
        3.943949238559487e-007,1.255398033240518e-005
        -3.943949238559341e-007,-1.255398033240518e-005
        -3.943949238559568e-007,-1.255398033240518e-005
1               3.162277660168380e+000,0.000000000000000e+000
        2.000000000000000e+000,0.000000000000000e+000
        1.980453705393099e+000,-1.967499214255068e-001
        3.909258921380289e-006,3.934998428510137e-005
        -3.909258921380277e-006,-3.934998428510137e-005
        -3.909258921380287e-006,-3.934998428510137e-005


Here's what matches:
        0       frequency       frequency
        1       V(v1)   voltage
        2       V(vout) voltage
        3       I(C1)   device_current
        4       I(R1)   device_current
        5       I(V1)   device_current

提前谢谢你的帮助

Answer 1

当您以文本模式（默认）打开文件时，\r\n在您读取文件时会自动转换为\n，因此您不必担心您使用的是什么操作系统