`extract_from_osm` returns the same OSM vector data

[juanfonsecaLS1]

The current version of the function returns the same vector data that was extracted using osm_extract. Later in the process, when traffic counts are assigned to the road links, some long links with multiple junctions are assigned the same flow value, or in some cases multiple counts are valid for sections of the same OSM link.

The following is an example in Hull, the link with osm_id = 83912501 covers a long section of Beverly Road and there are multiple counts.

An alternative solution would be producing a new network with dodgr_to_sf after processing the OSM data within the extract_from_osm function.

graph <- dodgr::weight_streetnet(network)
network <- dodgr::dodgr_to_sf(graph)
graph <- dodgr::dodgr_contract_graph(graph)

This would require an additional step when the counts are bi-directional as in the DfT dataset.

[juanfonsecaLS1]

I have also found that the junctions object that is exported by the function does contain duplicates. This part of the code is where the junctions are extracted:

# Find Junctions
  graph <- dodgr::weight_streetnet(network)
  graph <- dodgr::dodgr_contract_graph(graph)
  graph <- dodgr::dodgr_to_sfc(graph)
  graph <- graph$geometry
  dodgr::clear_dodgr_cache()


  points <- sf::st_cast(graph, "POINT")
  junctions <- points[duplicated(points)]
  junctions <- sf::st_as_sf(junctions)

I will test the following approach to see if there is any impact on the subsequent steps:

graph <- dodgr::weight_streetnet(lines,
                                 keep_cols = c("name","ref","highway","junction","maxspeed","oneway")
                                 )
network<- dodgr::dodgr_to_sf(graph) 

graph_contr <- dodgr::dodgr_contract_graph(graph)
junctions <- dodgr::dodgr_vertices(graph_contr) |> sf::st_as_sf(coords = c("x","y"),crs = 4326)

This addresses both issues in the osm_extract function.

[Robinlovelace]

Great detective work, let me know if you want me to take a look...