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python - Regex not finding specific pair of hexadecimal character

问题描述

python 3.7.4

I've a *.csv that contains numerous instances of the character string

High School

and numerous instances of the hexadecimal-pair

C3 82

which I'd like remove.

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

As written it should print out which rows contain the pattern. With patt = "High School" everything works as expected. With patt = r'\xc3\x82' nothing gets found.

Any ideas?

标签： pythonpython-3.xregex

解决方案

诀窍是 1) 放弃寻找和显示每个事件的想法，并记住目标是删除所有事件和 2) 以二进制的方式思考。然后它变得简单，但有一些微妙之处：

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)

感谢所有回复。万岁！

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