nltk/nltk — pull request #807 by salamatin (2014-12-09 07:37:02+00:00)
Title: Fixed an issue when zipped resources couldn't have been loaded

`LookupError` is raised when I'm trying to load a zipped corpus (full error message at the bottom).

The zip is there and successfully found — error happens when `ZipFilePathPointer` is accessing a path within the file. Code on line 452

# Normalize the entry string, it should be absolute:
entry = normalize_resource_name(entry, False, '/').lstrip('/')

returns this:

>>> data.normalize_resource_name('/dir/file', allow_relative=False, '/').lstrip('/')
'C:/dir/file'

and of course, such an entry cannot be found within a zipfile. In case of a zipfile, `allow_relative` should be set to `True`. This way `os.path.abspath()` function will not be called, and we get a proper path within the archive:

>>> data.normalize_resource_name('/dir/file', True, '/').lstrip('/')
'dir/file'

---
>>> reuters

>>> reuters.fileids()
Traceback (most recent call last):
File "C:\Python34\lib\site-packages\nltk\corpus\util.py", line 64, in __load
try: root = nltk.data.find('corpora/%s' % zip_name)
File "C:\Python34\lib\site-packages\nltk\data.py", line 618, in find
raise LookupError(resource_not_found)
LookupError:
**********************************************************************
Resource 'corpora/reuters.zip/reuters/' not found. Please use
the NLTK Downloader to obtain the resource: >>> nltk.download()
Searched in:
- 'C:\\Users\\Andrey/nltk_data'
- 'C:\\nltk_data'
- 'D:\\nltk_data'
- 'E:\\nltk_data'
- 'C:\\Python34\\nltk_data'
- 'C:\\Python34\\lib\\nltk_data'
- 'C:\\Users\\Andrey\\AppData\\Roaming\\nltk_data'
**********************************************************************

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "", line 1, in
File "C:\Python34\lib\site-packages\nltk\corpus\util.py", line 100, in __getattr__
self.__load()
File "C:\Python34\lib\site-packages\nltk\corpus\util.py", line 65, in __load
except LookupError: raise e
File "C:\Python34\lib\site-packages\nltk\corpus\util.py", line 62, in __load
root = nltk.data.find('corpora/%s' % self.__name)
File "C:\Python34\lib\site-packages\nltk\data.py", line 618, in find
raise LookupError(resource_not_found)
LookupError:
**********************************************************************
Resource 'corpora/reuters' not found. Please use the NLTK
Downloader to obtain the resource: >>> nltk.download()
Searched in:
- 'C:\\Users\\Andrey/nltk_data'
- 'C:\\nltk_data'
- 'D:\\nltk_data'
- 'E:\\nltk_data'
- 'C:\\Python34\\nltk_data'
- 'C:\\Python34\\lib\\nltk_data'
- 'C:\\Users\\Andrey\\AppData\\Roaming\\nltk_data'
**********************************************************************