Fitting dimension reduction methods to data lying on two-dimensional sphere.
This package provides principal geodesic analysis, principal circle, principal curves
proposed by Hauberg, and spherical principal curves. Moreover, it offers the method of locally
defined principal geodesics which is underway. The detailed procedures
are described in Lee, J., Kim, J.-H. and Oh, H.-S. (2021) .
Also see Kim, J.-H., Lee, J. and Oh, H.-S. (2020) .