Read TransportNetworks directly from kryo files

[owenam]

Currently, r5py builds a (python+java)TransportNetwork from a directory containing OSM and GTFS files, or from explictly-named OSM and GTFS files. These networks have to be rebuilt every time the same inputs are used. R5 provides methods for using Kryo to serialize/deserialize (java)TransportNetwork objects to/from arbitrary individual files, so that the network can be reloaded in the future without having to rebuild it from the OSM and GTFS inputs. Making use of this interface would be a big gain in flexibility for r5py.

The serialization/deserialization interface is in com.conveyal.r5.kyro.KryoNetworkSerializer.

I propose implementing this in (python)TransportNetwork by:

• Moving most existing TransportNetwork.__init__() code to a new TransportNetwork.build_from_sources() method
• Adding a TransportNetwork.load_network() method to read from a Kryo-serialized file
• Rewriting TransportNetwork.__init__() to parse an input list of files or directory to decide which of the methods to use

There's a variety of reasonable ways to name/arrange this all.

r5r does something similar via a Java implementation in org.ipea.r5r.Network.NetworkBuilder

This is something that I'd be happy to prototype following some discussion of naming and organization.

[owenam]

The discussion over at r5r in ipeaGIT/r5r#350 suggests that this might be entangled with ongoing JDK and Kryo version updates in R5: conveyal/r5#760

[christophfink]

The discussion over at r5r in ipeaGIT/r5r#350 suggests that this might be entangled with ongoing JDK and Kryo version updates in R5: conveyal/r5#760

That would be fantastic, some of the library versions used have been deprecated for a while now

[owenam]

We're finding it easy to work with the current 'build-every-time' approach, so I'm not going to pursue this in the short term. Because of the interaction with Kryo and JDK version, it seems like it will be a good time to revisit once R5 and r5py have digested the update from Java 11 to Java 21 which has been merged into R5's dev branch.

[abyrd]

Hi everyone! We thought you might be interested in this: https://github.com/conveyal/r5/releases/tag/v7.0

[christophfink]

Hi everyone! We thought you might be interested in this: https://github.com/conveyal/r5/releases/tag/v7.0

Hi! We actually bumped the R5 version in main, already (PR #385), so next r5py release is definitely building up on v7.0 :) Thanks for the heads-up!