These descriptors are described in
Vijay H.Masandand Vesna Rastija, PyDescriptor: A new PyMOL plugin for calculating thousands of easily understandable molecular descriptors, Chemometrics and Intelligent Laboratory Systems, 2017, 169, 12-18.
The implementation uses OpenSource version of PyMol. The source code to calculate the descriptors is available on the request from the authors. Contact Dr. Vijay Masand.