The number of occurrences of statistical characters

[RobertW]

who can help me to resolve the question,thanks 

# -*- coding:utf-8 -*-
# python 3.x
import re

patter = [chr(i) for i in range(33,126)]

with open("a.txt","r") as file:
    content = file.read()
    for i in patter:
        result = len(re.findall(r"[%s]" % i,content))
        if result != 0:
            print("%s:%d" % (i, result))

Error:
Traceback (most recent call last):
  File "D:\robot\desk\Script\login_Discuz.py", line 13, in <module>
    result = len(re.findall(r"[%s]" % i,content))
  File "D:\Python\Python36-32\lib\re.py", line 222, in findall
    return _compile(pattern, flags).findall(string)
  File "D:\Python\Python36-32\lib\re.py", line 301, in _compile
    p = sre_compile.compile(pattern, flags)
  File "D:\Python\Python36-32\lib\sre_compile.py", line 562, in compile
    p = sre_parse.parse(p, flags)
  File "D:\Python\Python36-32\lib\sre_parse.py", line 855, in parse
    p = _parse_sub(source, pattern, flags & SRE_FLAG_VERBOSE, 0)
  File "D:\Python\Python36-32\lib\sre_parse.py", line 416, in _parse_sub
    not nested and not items))
  File "D:\Python\Python36-32\lib\sre_parse.py", line 523, in _parse
    source.tell() - here)
sre_constants.error: unterminated character set at position 0

[buran]

There are special characters that need to be escaped if you want to use them literally. The error comes at the \ which is RegEx own escape char. So the result is (when not escaped) is invalid pattern.

import re, sre_constants
 
patter = [chr(i) for i in range(33,126)]
 
with open("a.txt","r") as file:
    content = file.read()
    for i in patter:
        try:
            result = len(re.findall(r"[%s]" % i,content))
        except sre_constants.error:
            print('error with {}'.format(i))

Output:
error with \
error with ^

change the for body like this

        try:
            result = len(re.findall(r"[%s]" % i,content))
        except sre_constants.error:
            result = len(re.findall(r"[\%s]" % i,content))
        if result != 0:
            print("%s:%d" % (i, result))  

and it work.

That said, note that you also need to escape chars like *, ? or . in order to search for them literally. I will leave this to you

[RobertW]

thanks a lot! U are right,I'll be carefull about escape chars like*,?or.

[nilamo]

You can also use the re.escape method, to escape the strings before building a regex with it.

Before:

>>> import re
>>> [re.compile(r"[{0}]".format(chr(i))) for i in range(33, 126)]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 1, in <listcomp>
  File "C:\Users\_\AppData\Local\Programs\Python\Python35-32\lib\re.py", line 224, in compile
    return _compile(pattern, flags)
  File "C:\Users\_\AppData\Local\Programs\Python\Python35-32\lib\re.py", line 293, in _compile
    p = sre_compile.compile(pattern, flags)
  File "C:\Users\_\AppData\Local\Programs\Python\Python35-32\lib\sre_compile.py", line 536, in compile
    p = sre_parse.parse(p, flags)
  File "C:\Users\_\AppData\Local\Programs\Python\Python35-32\lib\sre_parse.py", line 829, in parse
    p = _parse_sub(source, pattern, 0)
  File "C:\Users\_\AppData\Local\Programs\Python\Python35-32\lib\sre_parse.py", line 437, in _parse_sub
    itemsappend(_parse(source, state))
  File "C:\Users\_\AppData\Local\Programs\Python\Python35-32\lib\sre_parse.py", line 545, in _parse
    source.tell() - here)
sre_constants.error: unterminated character set at position 0

After:

>>> [re.compile(r"[{0}]".format(re.escape(chr(i)))) for i in range(33, 126)]
[re.compile('[\\!]'), re.compile('[\\"]'), re.compile('[\\#]'), re.compile('[\\$]'), re.compile('[\\%]'), re.compile('[\\&]'), re.compile("[\\']"), re.compile('[\\(]'), re.compile('[\\)]'), re.compile('[\\*]'), re.compile('[\\+]'), re.compile('[\\,]'), 
#snipped