在python中，如何使用regex对我们从文件中读取的数据只记录字符串中匹配的部分？

Question

如何从从文本文件读取的行中打印与regex匹配的字符串的唯一部分。我有下面的代码。

filename = "C:/Users/Desktop/netlist"
pattern = re.compile('^[A-Z]{1,2}\d{1,3} ')
with open(filename, "rt") as myfile:
    for line in myfile:
        if pattern.search(line) != None:
            print(line, end='')

但这给了我一整排的火柴。

我试过的另一件事是。

k = []
filename = "C:/Users/Desktop/netlist"
pattern = re.compile('^[A-Z]{1,2}\d{1,3}')
with open(filename, "rt") as myfile:
   for line in myfile:
       if pattern.match(line) != None:
        k.append(pattern.search(line))

但这是作为re.Match对象而不是列表出现的。

[<re.Match object; span=(0, 3), match='NM4'>,
<re.Match object; span=(0, 3), match='NM3'>,
<re.Match object; span=(0, 2), match='M9'>,
<re.Match object; span=(0, 2), match='M7'>,
<re.Match object; span=(0, 2), match='M5'>,
<re.Match object; span=(0, 2), match='M2'>]

我的输入看起来是：

NM4 (net19 net19 0 0) nmos1 w=(5.65u) l=410n as=3.39p ad=3.39p ps=12.5u \
NM3 (net28 net19 0 0) nmos1 w=(5.65u) l=410n as=3.39p ad=3.39p ps=12.5u \
M9 (vout\+ net19 0 0) nmos1 w=(12.71u) l=310n as=7.626p ad=7.626p \
M7 (vout\- net19 0 0) nmos1 w=(12.71u) l=310n as=7.626p ad=7.626p \
M5 (net7 net19 0 0) nmos1 w=(2u) l=180n as=1.2p ad=1.2p ps=5.2u pd=5.2u \
M2 (net8 Vin\- net7 0) nmos1 w=(28.25u) l=410n as=16.95p ad=16.95p \

我期待着我的回答是：

[NM4 NM3 M9 M7 M5 M2]

Answer 1

使用regex分组'([A-Z]{1,2}\d{1,3})'

Ex:

k = []
filename = "C:/Users/Desktop/netlist"
pattern = re.compile('([A-Z]{1,2}\d{1,3})')
with open(filename, "rt") as myfile:
    for line in myfile:
        m = pattern.match(line)
        if m:                       #Check if data. 
            k.append(m.group(1))    #Fetch result.

print(k) #['NM4', 'NM3', 'M9', 'M7', 'M5', 'M2']