ab_json() is slow

[Robinlovelace]

No description provided.

[Robinlovelace]

Not totally reproducible example showing the example in the README takes ~30s on a decent computer, 10 times slower than creating the sf object. That is way too slow. Not sure exactly how best to speed this up but sure it's possible. In the meantime I suggest using only a sample of the OD data in the readme to create a minimal example.

> system.time({output_sf = ab_scenario(
+     od = montlake_od,
+     zones = montlake_zones,
+     zones_d = NULL,
+     origin_buildings = montlake_buildings,
+     destination_buildings = montlake_buildings,
+     pop_var = 3,
+     time_fun = ab_time_normal,
+     output = "sf",
+     modes = c("Walk", "Bike", "Drive", "Transit")
+ )})
0 origins with no match in zone ids
0 destinations with no match in zone ids
 points not in od data removed.
   user  system elapsed 
  2.369   0.024   2.418 
Warning messages:
1: In st_centroid.sf(origin_buildings) :
  st_centroid assumes attributes are constant over geometries of x
2: In st_centroid.sf(destination_buildings) :
  st_centroid assumes attributes are constant over geometries of x
> system.time({output_json = ab_json(output_sf, time_fun = ab_time_normal, scenario_name = "Montlake Example")
+ })
   user  system elapsed 
 28.435   0.149  28.607 

[natesheehan]

@Robinlovelace are you still wanting to look at this? Right now don't think it's too much of a pressing issue?

[Robinlovelace]

Not much of a pressing issue, agreed. Yes still want to look at it, I guess there are good ways to speed it up so worth keeping open but not on the immediate todo list...

[natesheehan]

adding this here for rust helping us speed things up

https://github.com/dabreegster/odjitter
https://github.com/robinlovelace/georustr