NGT installation for Mac OSX

This article captures the changes required to install the Neighbourhood Graph and Tree for Indexing on Mac OSX.
The GitHub repo is available here: https://github.com/yahoojapan/NGT

Initial NGT Installation

      $ unzip NGT-x.x.x.zip

      $ cd NGT-x.x.x

      $ mkdir build

      $ cd build

      $ cmake .. ## (for non-MAC)

For Mac OSX, the above command needs to be replaced with the below one. Also, need to install GNU cc/c++ from brew.

      $ cmake -DCMAKE_C_COMPILER=/usr/local/bin/gcc-8 -DCMAKE_CXX_COMPILER=/usr/local/bin/g++-8 ..

      $ make

      $ make install

      $ ldconfig

The above 'ldconfig' command works for Linux/Unix. For Mac OSX, it has to be:

      $ sudo update_dyld_shared_cache

NGT Python installation

$ cd NGT_ROOT/python

$ python setup.py sdist

$ pip install dist/ngt-1.2.0.tar.gz

For the above command, use the following command (after GNU cc/c++ installed)

$ env CC=/usr/local/bin/gcc-8 CXX=/usr/local/bin/g++-8 pip install dist/ngt-1.2.0.tar.gz