[pgrouting-dev] A roadmap

[Vicky Vergara]

Hello fellow developers,

As you know we are rewriting pgRouting, since v2.1, to remove all "bugs",
like the non standard way of constructing a graph, and using more C++
features.

The rewrite is "almost done":

**First pair of functions**

   - pgr_alphaShape - Alpha shape computation
   - pgr_pointsAsPolygon - Polygon around a set of points

Both functions are tightly dependant, and I believe that they should be a
postGIS function as is a geometry function, and the closest one that
resembles this pair of functions is  ST_ConcaveHull [1] Some time ago I
compared both functions on [2]

I went to see how to add that function to postGIS, and for the moment that
is not possible, it sould be done first in GEOS, and  GEOS is so big, right
now I dont feel is the time to do that, but rewriting to use boost:Geometry
would eliminate the need of CGAL, so one less pre-requisite to build
pgRouting would be needed. or they can stay as they are now.


**The other function is pgr_trsp**

Which has so many problems at postgres level [4], Last year on GSoC, Vidham
tried to do a rewrite, confirming that the problem is much harder than
expected for the 3 month program. But as far as I know many people use them
because it has the "points" version.
The C++ code is not well designed [5], just a look at that, my_dijkstra
calls my_dijkstra and that calls my_dijkstra, it still uses pointers, so
great chance of memory leaks, etc.
Basically is **Use at your own risk**


Beside those functions mentioned above, now we are in the moment where
there are  more proposed functions [7] than official functions. and a lot
of deprecated functions that have to be maintained and tested because of
backwards compatibility.

** So, here is my road map #1 **

Version 2.7 to be released on September 2018 where fix bug of
pgr_withPoints [8] is a must have, and the possibilities of what other
things it could have:
- New functionality done by GSoC students on "experimental section"
- Write a substitution (with a different name maybe pgr_dijkstraTR) for
pgr_trsp (one vertex to one vertex) based on dijkstra
- Rewrite pgr_alphaShape to use boost:graph instead of CGAL
- move some experimental functions up to proposed

Version 3.0 I would like it to be on September 2019
Where a complete cleanup of the deprecated functions would be done,
Move proposed functions to official pgRouting functions.

** So, here is my road map #2 **

Version 3.0 to be released on March 2019 where fix bug of pgr_withPoints
[8] and Complete cleanup of the deprecated functions are a must have, and
the possibilities of what other things it could have:
- New functionality done by GSoC students on "experimental section"
- Write a substitution (with a different name maybe pgr_dijkstraTR) for
pgr_trsp (one vertex to one vertex) based on dijkstra
- Rewrite pgr_alphaShape to use boost:graph instead of CGAL
- move some experimental functions up to proposed
- Move proposed functions to official pgRouting functions.

Probably this second road map will make the second version of the pgRouting
book a little easier to write, (please Robe, comment on this)


We would like comments from the community about both road maps and if
possible  to test proposed functions and experimental functions to help
decide which proposed functions can go up one level. (don't forget to open
issues)

Regards
pgRouting team


[1] https://postgis.net/docs/ST_ConcaveHull.html
[2] https://github.com/cvvergara/pgrouting/issues/57
[3]
https://github.com/pgRouting/pgrouting/blob/master/sql/alpha_shape/alpha_shape.sql#L62
[4] https://github.com/pgRouting/pgrouting/tree/master/doc/trsp
[
​5]
https://github.com/pgRouting/pgrouting/blob/master/include/trsp/GraphDefinition.h#L94
​

[
​6] https://github.com/pgRouting/pgrouting/tree/master/sql/pickDeliver​

[
​7] http://docs.pgrouting.org/latest/en/proposed.html
[8] https://github.com/pgRouting/pgrouting/issues/760​

-- 

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81739 München, Germany

Vicky Vergara
Operations Research

eMail: vicky at georepublic.de
Web: https://georepublic.info

Tel: +49 (089) 4161 7698-1
Fax: +49 (089) 4161 7698-9

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