How to detect non-ASCII character in Python?

Question

I’m parsing multiple XML files with Python 2.7, there are some strings like: string ="[2,3,13,37–41,43,44,46]". I split them to get a list of all elements, and then I have to detect elements with “–” like “37–41”, but it turns out this is not a regular dash, it’s a non-ASCII character:

elements = [u'2', u'3', u'13', u'37u201341', u'43', u'44', u'46']

So I need something like

for e in elements:
  if "–" in e:
      # do something about it

If use that non-ASCII char in this if expression, then I get an error: "SyntaxError: Non-ASCII character 'xe2' in file...".

I tried to replace the if expression with this re method:

re.search('xe2', e)

but it’s not the case again. So I’m looking for a way to either convert that non-ASCII char to a regular ASCII “-” or use the ASCII number directly in the search expression.

Asked By: sheshkovsky

||

Source

Answer 1

Give this a try:

>>> import re
>>> non_decimal = re.compile(r'[^d.]+')
>>>
>>> string ="[2,3,13,37–41,43,44,46]"
>>> new_str = string.replace("[","")
>>> new_str = new_str.replace("]","")
>>> lst = new_str.split(",")
>>> for element in lst:
    if element.isdigit():
        print element
    else:
        toexpand = non_decimal.sub('f', str(element))
        toexpand = toexpand.split("f")
        for i in range(int(toexpand[0]),int(toexpand[1])+1,1):
            print i


2
3
13
37
38
39
40
41
43
44
46
>>>

Answered By: EbraHim

Answer 2

You have to declare your encoding in your Python program, for example:

# -*- coding: utf-8 -*-

Usually Python tells you about this issue:

SyntaxError: Non-ASCII character ‘xe2’ in file ./fail.py on line 3, but no encoding declared; see http://www.python.org/peps/pep-0263.html for details

After adding the encoying, your code should work just fine.

Answered By: Schore

Answer 3

# -*- coding: utf-8 -*-

import re

elements = [u'2', u'3', u'13', u'37u201341', u'43', u'44', u'46']

for e in elements:
    if (re.sub('[ -~]', '', e)) != "":
        #do something here
        print "-"

re.sub('[ -~]', '', e) will strip out any valid ASCII characters in e (Specifically, replace any valid ASCII characters with “”), only non-ASCII characters of e are remained.

Hope this help

Answered By: ilovecomputer

Answer 4

You can check the if the character value is between 0 – 127.

for c in someString:
    if 0 <= ord(c) <= 127:
        # this is a ascii character.
    else:
        # this is a non-ascii character. Do something.

Answered By: okorkut

Answer 5

This may not answer your whole question. Way too simple and not flexible. I do this whenever I have this error.

I usually open up an interactive python shell and I type in:

print [ln for ln in open("filename.py", "rb").readlines() if "xe2" in ln]

That gives you lines with ex2. Then try finding it in your editor.and try removing the character.

Answered By: hungryWolf

Answer 6

For a more generalized approach you can use libraries such as chardet (pure python) or cchardet (a faster C alternative). Install the module with e.g. with pip3 install chardet or pip3 install cchardet.

They both have the same API:

import chardet

with open("/etc/hosts", "rb") as fi:
    print(chardet.detect(fi.read()))

# OUTPUT: 
# {'encoding': 'ascii', 'confidence': 1.0, 'language': ''}

If the encoding key in the dict is not ascii then you have non-ascii characters in the file.

Both modules expose command line tools that you can use to detect which of your XML files are non-ASCII:

find . -iname "*.xml" -exec cchardetect {} +

Normally, you would only need to do the detection when working with mysterious legacy data of unknown origin that is not utf-8/unicode.

If you have a hard requirement to convert everything to ASCII then you can do something like:

import unicodedata

unicodedata.normalize('NFKD', 'Verhältnismäßigkeit — 1').encode('ascii', 'ignore')
# OUTPUT
# b'Verhaltnismaigkeit  1'

Answered By: ccpizza

How to detect non-ASCII character in Python?

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