Hopkins statistic
R function to calculate the Hopkins statistic of clustering tendency (H).
See this blog entry for why to calculate the Hopkins statistic: https://www.r-bloggers.com/assessing-clustering-tendency-a-vital-issue-unsupervised-machine-learning/
However, this blog (and the origial one this one is derived from) contain a mismatch between the equation for H and the implementation in the packages "clustertend" and "factoextra". The equation says that the H should increase with clustering tendency, but the clusterdata and factoextra implementations do the opposite (they calculate 1-H).
The function provided here implements H as per the equation which is also defined in the Wikipedia: https://en.wikipedia.org/wiki/Hopkins_statistic.
It also uses the FNN package providing a much faster implementation compared to both "clustertend" and "factoextra".