Implementation of cppRouting with Dijkstra algorithm.

[latot]

Hi all, I has been able to sfnetworks, it simplifies a lot how to work with networks in R.

All this from: #250

At the same time, operations to construct distances matrix or paths sadly are not very fast, due to that I have some code that is able to connect cppRouting with sfnetworks, the lib implements the Dijkstra algorithm, and is designed with optimization in mind.

https://github.com/vlarmet/cppRouting

I have tested it before, and calculations that I was not able to finish in hours with sfnetworks functions I was able to run them in seconds with this lib.

I think it would give a great benefit to sfnetworks.

I prepared a mini-repo with the examples of how to compute everything of this using sfnetworks.

https://github.com/latot/sample_sfnetworks_cppRouting

Is not hard to read, every file describe one function, and how is transform from/to the data between them, the input of all the data are nodes id, the output is always a dataframe with "from"/"to" columns and a "distance"/"path" with the results (path is a geom column).

I hope this code could be implemented, or works as a base to incorporate the lib on sfnetworks.

Thx!