Sol Sol - 1 month ago 13
Python Question

Python version/import confusion

I'm trying to get this Python 2.7 code to work.

https://github.com/slanglab/phrasemachine

I've downloaded and unzipped the repo from github. Here's what happens when I try to run the code.

phrasemachine$ python
Python 2.7.10 (default, Oct 23 2015, 19:19:21)
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import phrasemachine
>>> text = "Barack Obama supports expanding social security."
>>> print phrasemachine.get_phrases(text)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "phrasemachine.py", line 253, in get_phrases
tagger = TAGGER_NAMES[tagger]()
File "phrasemachine.py", line 166, in get_stdeng_nltk_tagger
tagger = NLTKTagger()
File "phrasemachine.py", line 133, in __init__
import nltk


ImportError: No module named nltk

So, I need the nltk module. I have that installed here:

Sure enough, Python 2 doesn't know about nltk.

phrasemachine$ python
Python 2.7.10 (default, Oct 23 2015, 19:19:21)
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import nltk
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named nltk


But, Python 3 does.

phrasemachine$ python3
Python 3.5.1 (v3.5.1:37a07cee5969, Dec 5 2015, 21:12:44)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import nltk
>>>


Pip tells me that nltk is already installed, but for 3.5.

$ sudo pip install -U nltk
Requirement already up-to-date: nltk in /Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/nltk-3.2.1-py3.5.egg


Update 10/10/16: I installed the 2.7 version of Python via brew, which give me the 2.7 pip.

$ /usr/local/bin/pip --version
pip 8.1.2 from /usr/local/lib/python2.7/site-packages (python 2.7)


Then I installed nltk with that pip:

$ sudo /usr/local/bin/pip install -U nltk
Password:
The directory '/Users/me/Library/Caches/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/Users/me/Library/Caches/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Collecting nltk
Downloading nltk-3.2.1.tar.gz (1.1MB)
100% |████████████████████████████████| 1.1MB 683kB/s
Installing collected packages: nltk
Running setup.py install for nltk ... done
Successfully installed nltk-3.2.1


It says it installed nltk but the warnings are concerning. And, Python 2.7 still fails to import nltk.

$ python
Python 2.7.10 (default, Oct 23 2015, 19:19:21)
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import phrasemachine
>>> text = "Barack Obama supports expanding social security."
>>> print phrasemachine.get_phrases(text)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "phrasemachine.py", line 253, in get_phrases
tagger = TAGGER_NAMES[tagger]()
File "phrasemachine.py", line 166, in get_stdeng_nltk_tagger
tagger = NLTKTagger()
File "phrasemachine.py", line 133, in __init__
import nltk
ImportError: No module named nltk
>>> import nltk
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named nltk


Final update! I pointed Python 2.7 to the site packages directory where Homebrew installs stuff and I'm now good!

>>> import sys
>>> sys.path.append('/usr/local/lib/python2.7/site-packages')

Answer

Since you have two python distributions, you also need two versions of pip. Find out where your pip executables are with which -a pip, and install pip for your Python 2.7 distribution if necessary. Then tell the pip that goes with Python 2.7 (perhaps /usr/local/bin/pip) to install the nltk.

(Edit: Pip must be able to find the proper Python on its PATH. I hadn't thought to go into this.)

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