A new package RcppAnnoy is now on CRAN.
It wraps the small, fast, and lightweight C++ template header library Annoy written by Erik Bernhardsson for use at Spotify.
While Annoy is setup for use by Python, RcppAnnoy offers the exact same functionality from R via Rcpp.
A new page for RcppAnnoy provides some more detail, example code and further links. See a recent blog post by Erik for a performance comparison of different approximate nearest neighbours libraries for Python.
This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.