仅打印与正则表达式Pandas匹配的字符串部分

Question

我有400个文件，其中包含多行。我想查找特定的行并仅提取/打印其中的一部分。

我想到达此行：

Full seesion name: T27I5E8_S1_N005_V004

并且仅打印：

S1_V004

我尝试过：

for filename in os.listdir(data_directory): 
     with open(data_directory + "/" + filename) as file:
        for line in file:
            if re.search(r'([S][\d])|([V][\d]{3})', line):
                    print(line)

但它会打印出整行。我也尝试过：

  subjID = re.compile(r'([S][\d])|([V][\d]{3})')

for filename in os.listdir(data_directory): 
     with open(data_directory + "/" + filename) as file:
        for line in file:
            print(subjID.findall(line))

但是输出看起来像：

  []
[]
[]
[]
[('S1', ''), ('', 'V094')]
[]
[]
[]
[]
[]
[]
[]
[('S1', ''), ('', 'V094')]
[]
[]
[]
[]
[]
[]
[]

Answer 1

您可以使用

for filename in os.listdir(data_directory): 
  with open(data_directory + "/" + filename) as file:
    for line in file:
      m = re.findall(r'(?<![^_])[SV]\d+(?![^_])', line)
      if len(m):
        print("_".join(m))

请参见Python demo和regex demo。使用re.findall，可以找到所有匹配项，如果找到，则结果是由匹配文本组成的_串联字符串。

图案详细信息

• [(?<![^_])-字符串或开始于_的位置]的位置>
• [[SV]-S或V
• \d+-1个以上的数字
• [(?![^_])-字符串或位置的末尾，紧跟着_。]]