RcppAnnoy 
Rcpp bindings for Annoy
What is Annoy?
Annoy is a small, fast and lightweight library for Approximate Nearest Neighbours with a particular focus on efficient memory use and the ability to load a pre-saved index.
Annoy is written by Erik Bernhardsson.
Why this package?
It provides a nice example for Rcpp Modules and use of templates: Annoy uses
a template data type (generally float for efficiency) and one of two
distance measures. This package shows that it is easy to wrap both.
Status
The package matches the behaviour of the original Python package in the
original Python wrapper for the Annoy
library. It also replicates all unit tests written for the Python frontend,
including a test for efficiently mmap-ing a binary index file.
The package originally built on Linux and OS X, and thanks to a patch by Qiang Kou now also builds on Windows.
Installation
You can either install from source via this repo, or install the CRAN package the usual way from R.
Author
Dirk Eddelbuettel
License
GPL (>= 2)