Transit schedules

[kylebarron]

Transit schedules

[kylebarron]

E.g the TripsLayerexample data looks like:

  {
    "vendor": 0,
    "path": [
      [-74.20986, 40.81773],
      [-74.20987, 40.81765],
      [-74.20998, 40.81746],
      [-74.21062, 40.81682],
      [-74.21002, 40.81644],
      [-74.21084, 40.81536],
      [-74.21142, 40.8146],
      [-74.20965, 40.81354],
      [-74.21166, 40.81158],
      [-74.21247, 40.81073],
      [-74.21294, 40.81019],
      [-74.21302, 40.81009],
      [-74.21055, 40.80768],
      [-74.20995, 40.80714],
      [-74.20674, 40.80398],
      [-74.20659, 40.80382],
      [-74.20634, 40.80352],
      [-74.20466, 40.80157]],
    "timestamps": [ 1191, 1193.803, 1205.321, 1249.883, 1277.923, 1333.85, 1373.257, 1451.769, 1527.939, 1560.114, 1579.966, 1583.555, 1660.904, 1678.797, 1779.882, 1784.858, 1793.853, 1868.948]
  }

[kylebarron]

Same number of timestamps as stops, so you could recreate something similar with the transit data

[kylebarron]

Keep everything in local time? I think the source data in the transit land schedule is local time with time zone included. So instead of dealing with time zones, just keep everything local

[kylebarron]

For the ui, have a small div at the bottom with a slider? Width 90% and max width what?

[kylebarron]

Have schedule data in a separate set of tiles, then load schedule data in a TileLayer, where each tile renders a sub layer that is a TripsLayer?

[kylebarron]

I'm thinking of having the TripsLayer use data from every ScheduleStopPair...

So if I get ScheduleStopPairs...

There's an n:1 correspondence from ScheduleStopPairs to RouteStopPatterns, but luckily it looks like n:1, not n:n, since every ScheduleStopPair apparently only has one route_stop_pattern_onestop_id it's attached to.

But note that you can't just get the origin and destination stop onestop_id from the ScheduleStopPair, since then you'll have a straight line from origin to destination. But also you can't directly use only the RouteStopPatterns, because that doesn't include where along the route the stops are. And also you can't assume the stop location is one of the RouteStopPatterns coordinates, because of line simplification.

So I think the process to get geometric ScheduleStopPairs is:

1. Get ScheduleStopPair. Call that ssp.
2. For that ssp, find the RouteStopPattern it's associated with.
3. For that ssp, find the Point locations of the origin and destination stops
4. For the origin and destination stops, find the closest point on the RouteStopPattern
5. Keep the LineString of the RouteStopPattern between the origin and destination coordinate
6. For each coordinate of the LineString between origin and destination, linearly interpolate the timestamp between the origin timestamp and destination timestamp. Shouldn't have to simplify more because the geometry should already be simplified from transitland.

Now you have data ready for the TripsLayer for every ScheduleStopPair

[kylebarron]

Figure out how to get a collection of ordered points with timestamps on the points

Well if you're sticking with tiled geojson, then just put the timestamps as the third value of the geojson

If you get all the line segments that intersect a given box, then there will be segments with one end outside of the box. So you can find segments that intersect, then find segments fully contained. And the segments that are not fully contained you can interpolate to cut at the edge of the box.

I think you did this when you were figuring out using vector tiles in deckgl?

[kylebarron]

Look at supermercado burn

supermercado/burntiles.py

[kylebarron]

Just use mercantile directly. Try to traverse the tree, I.e should be easy to find tiles at zoom ~8 with no routes, so don't check the children of that tile.

Or even better, start with the tile that encompasses the whole us, it must intersect, then take each of its children, check if each of them intersect, and so on, up to the desired zoom level. Since in this stage you're only searching if any route intersects, should be relatively fast. Once you get to the minzoom level, then it'll be slower to clip geojsons.

Would be nice to have a separate reusable function that clips linestrings by a bounding box (any geometry?) while adding interpolated points on the boundary.

[kylebarron]

Within each tile, coalesce each schedule stop pair by route stop pattern so that there are fewer individual linestrings?

[kylebarron]

Fixed by #18