MeCab UTF-8 Decoding Problem

[Terry Reedy]

On 6/29/2013 10:02 AM, Dave Angel wrote:
> On 06/29/2013 07:29 AM, fobos3 at gmail.com wrote:
>> Hi,
>
> Using Python 2.7 on Linux, presumably?  It'd be better to be explicit.
>
>>
>> I am trying to use a program called MeCab, which does syntax analysis
>> on Japanese text.

It is generally nice to give a link when asking about 3rd party 
software.  https://code.google.com/p/mecab/
In this case, nearly all the non-boilerplate text is Japanese ;-(.

 >> The problem I am having is that it returns a byte string

and the problem with bytes is that they can have any encoding.
In Python 2 (indicated by your print *statements*), a byte string is 
just a string.

>> and if I try to print it, it prints question marks for almost
>> all characters. However, if I try to use .decide, it throws an error.
>> Here is my code:
>
> What do the MeCab docs say the tagger.parse byte string represents?
> Maybe it's not text at all.  But surely it's not utf-8.

https://mecab.googlecode.com/svn/trunk/mecab/doc/index.html
MeCab: Yet Another Part-of-Speech and Morphological Analyzer
followed by Japanese.

>> #!/usr/bin/python
>> # -*- coding:utf-8 -*-
>>
>> import MeCab
>> tagger = MeCab.Tagger("-Owakati")
>> text = 'MeCabで遊んでみよう！'

Parts of this appear in the output, as indicated by spaces.
'MeCabで遊 んで みよ う！'

>> result = tagger.parse(text)
>> print result
>>
>> result = result.decode('utf-8')
>> print result
>>
>> And here is the output:
>>
>> MeCab �� �� ��んで�� �� ��う！

Python normally prints bytes with ascii chars representing either 
themselves or other values with hex escapes. This looks more like 
unicode sent to a terminal with a limited character set. I would add

print type(result)

to be sure.

>> Traceback (most recent call last):
>>    File "test.py", line 11, in <module>
>>      result = result.decode('utf-8')
>>    File "/usr/lib/python2.7/encodings/utf_8.py", line 16, in decode
>>      return codecs.utf_8_decode(input, errors, True)
>> UnicodeDecodeError: 'utf8' codec can't decode bytes in position 6-7:
>> invalid continuation byte
>>
>>
>> ------------------
>> (program exited with code: 1)
>> Press return to continue
>>
>> Also my terminal is able to display Japanese characters properly. For
>> example print '日本語' works perfectly fine.


-- 
Terry Jan Reedy