正則表達式找不到特定的十六進制字符對

Question

python 3.7.4

我有一個 *.csv 包含許多字符串實例

High School

以及許多十六進制對的實例

C3 82

我想刪除。

def findem( fn, patt):
  p = re.compile(patt)
  with open( fn, newline = '\n') as fp:
    for line in fp.readlines():
      m = p.search( line)
      if( m):
        print('found {0}'.format(line))

fn_inn = "Contacts_prod.csv"

patt_hs   = "High School"
patt_C382 = r'\\xC3\\x82'

print('trying patt_hs')
findem( fn_inn, patt_hs)    # <------- finds all rows containing High School, great

print('trying patt_C382')
findem( fn_inn, patt_C382)  # <------- doesnt find anything and should

正如所寫的那樣，它應該打印出哪些行包含該模式。 使用patt = "High School"一切都按預期工作。 使用patt = r'\xc3\x82'什么都找不到。

有任何想法嗎？

Answer 1

訣竅是 1) 放棄尋找和顯示每個事件的想法，並記住目標是刪除所有事件和 2) 以二進制的方式思考。 然后它變得簡單，但有一些微妙之處：

def findem( patt):
  p = re.compile(patt)
  with open( fn_out, 'wb') as fp_out:   #binary input
    with open( fn_inn, 'rb') as fp_inn: #binary output
      slurp_i = fp_inn.read()           # slurp_i is of type bytes
      slurp_o = p.sub( b'', slurp_i)    # notice the b'' , very subtle
      fp_out.write( slurp_o)

fn_inn = "Contacts_prod.csv"
fn_out = "Contacts_prod.fixed.dat"

patt = re.compile(b'\xC3\x82')         # notice the b'' instead of r'', very subtle
findem( patt)

感謝所有回復。 萬歲！

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