Multi-dimensional unfolding is a procedure to recover positions of two sets of points from a matrix of distances between the points of both groups. For some of my research work, I implemented the algorithm for metric multi-dimensional unfolding that Peter Schönemann published back in 1970 in Psychometrika. This is not the most advanced algorithm, however it is quite robust and quick when a large number of points is involved. Note that it is an algorithm for *metric* unfolding. That is, the input data need to be interpretable as real distances.

The package that contains my implementation of Schönemann’s algorithm is called *munfold*. It is now published on CRAN. Development occurs on GitHub, where both releases and the development tree can be found.