ImportError: No module named '_swigfaiss

[shashi-netra]

Summary

Installed faiss using pip3 on Ubuntu 16 (cpu)

I am unable to import faiss into python3 and it results in the following error
ImportError: No module named '_swigfaiss'

See error log below, I have installed (and re-installed!) libomp but no luck.
What could possibly be wrong?

Platform

Ubuntu 16 & Python3

Running on:

• [x ] CPU
• GPU

Interface:

• C++
• Python

Reproduction instructions

import faiss```

<!-- Please provide specific and comprehensive instructions to reproduce the
described behavior. -->

```Python 3.5.2 (default, Nov 12 2018, 13:43:14) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import faiss
Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/faiss/swigfaiss.py", line 14, in swig_import_helper
    return importlib.import_module(mname)
  File "/usr/lib/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 666, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 577, in module_from_spec
  File "<frozen importlib._bootstrap_external>", line 906, in create_module
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
ImportError: libomp.so: cannot open shared object file: No such file or directory

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.5/dist-packages/faiss/__init__.py", line 19, in <module>
    from .swigfaiss import *
  File "/usr/local/lib/python3.5/dist-packages/faiss/swigfaiss.py", line 17, in <module>
    _swigfaiss = swig_import_helper()
  File "/usr/local/lib/python3.5/dist-packages/faiss/swigfaiss.py", line 16, in swig_import_helper
    return importlib.import_module('_swigfaiss')
  File "/usr/lib/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
ImportError: No module named '_swigfaiss'
>>> 

[beauby]

The loader cannot find libomp.so. Where do you have it installed?

[shashi-netra]

Ok I figured it out, I needed to install openMP and did so using this:
sudo apt-get install libomp-dev

[xxllp]

how to do on centos sys ,@shashi-netra

[flynnzhao]

It should not be so：

pip install faiss

should do：

CPU version only

conda install faiss-cpu -c pytorch

GPU version

conda install faiss-gpu cudatoolkit=8.0 -c pytorch # For CUDA8
conda install faiss-gpu cudatoolkit=9.0 -c pytorch # For CUDA9
conda install faiss-gpu cudatoolkit=10.0 -c pytorch # For CUDA10

link: https://github.com/facebookresearch/faiss/blob/master/INSTALL.md

[hzitoun]

conda install faiss-cpu -c pytorch instead of pip install faiss makes everything work

[Arjunsankarlal]

For those who are working with pip and not conda, if you have installed it with,

pip install faiss

uninstall it. And then install faiss with,

pip install faiss-cpu --no-cache

This worked for me 👍

[dvlshah]

Just install three things in the following order and your problem Is solved

pip3 install faiss
sudo apt-get install libopenblas-dev
sudo apt-get install libomp-dev

[RaviTezu]

Thank you @Arjunsankarlal.

I am on Mac and I had to remove both the faiss and faiss-cpu packages before installing faiss-cpu again.

Mac users:

1. Uninstall both the faiss and faiss-cpu using: pip uninstall -y faiss faiss-cpu
2. Install faiss-cpu only: pip install faiss-cpu --no-cache

Once installed you may see the below error:

ImportError: dlopen(/Users/ravitezu/.virtualenvs/myproject/lib/python3.6/site-packages/faiss/_swigfaiss.cpython-36m-darwin.so, 2): Library not loaded: /usr/local/opt/libomp/lib/libomp.dylib
  Referenced from: /Users/ravitezu/.virtualenvs/myproject/lib/python3.6/site-packages/faiss/_swigfaiss.cpython-36m-darwin.so
  Reason: image not found

You can fix the above error by installing the libomp package using: brew install libomp.
Hope this helps.

[YuanCao1996]

For those who are working with pip and not conda, if you have installed it with,

pip install faiss

uninstall it. And then install faiss with,

pip install faiss-cpu --no-cache

This worked for me 👍

Thanks a lot! it's really helpful.