dodgr_streetnet_sc: Extract a street network in 'silicate'-format for a given...

In dodgr: Distances on Directed Graphs

Extract a street network in silicate-format for a given location.

Description

Use the osmdata package to extract the street network for a given location and return it in SC-format. For routing between a given set of points (passed as pts), the bbox argument may be omitted, in which case a bounding box will be constructed by expanding the range of pts by the relative amount of expand.

Usage

dodgr_streetnet_sc(bbox, pts = NULL, expand = 0.05, quiet = TRUE)

Arguments

bbox	Bounding box as vector or matrix of coordinates, or location name. Passed to osmdata::getbb.
pts	List of points presumably containing spatial coordinates
expand	Relative factor by which street network should extend beyond limits defined by pts (only if bbox not given).
quiet	If FALSE, display progress messages

Value

A Simple Features (sf) object with coordinates of all lines in the street network.

Note

Calls to this function may return "General overpass server error" with a note that "Query timed out." The overpass served used to access the data has a sophisticated queueing system which prioritises requests that are likely to require little time. These timeout errors can thus generally not be circumvented by changing "timeout" options on the HTTP requests, and should rather be interpreted to indicate that a request is too large, and may need to be refined, or somehow broken up into smaller queries.

See Also

Other extraction: dodgr_streetnet(), weight_railway(), weight_streetnet()

Examples

## Not run: 
streetnet <- dodgr_streetnet ("hampi india", expand = 0)
# convert to form needed for `dodgr` functions:
graph <- weight_streetnet (streetnet)
nrow (graph) # around 5,900 edges
# Alternative ways of extracting street networks by using a small selection
# of graph vertices to define bounding box:
verts <- dodgr_vertices (graph)
verts <- verts [sample (nrow (verts), size = 200), ]
streetnet <- dodgr_streetnet (pts = verts, expand = 0)
graph <- weight_streetnet (streetnet)
nrow (graph)
# This will generally have many more rows because most street networks
# include streets that extend considerably beyond the specified bounding box.

# bbox can also be a polygon:
bb <- osmdata::getbb ("gent belgium") # rectangular bbox
nrow (dodgr_streetnet (bbox = bb)) # around 30,000
bb <- osmdata::getbb ("gent belgium", format_out = "polygon")
nrow (dodgr_streetnet (bbox = bb)) # around 17,000
# The latter has fewer rows because only edges within polygon are returned

# Example with access restrictions
bbox <- c (-122.2935, 47.62663, -122.28, 47.63289)
x <- dodgr_streetnet_sc (bbox)
net <- weight_streetnet (x, keep_cols = "access", turn_penalty = TRUE)
# has many streets with "access" = "private"; these can be removed like this:
net2 <- net [which (!net$access != "private"), ]
# or modified in some other way such as strongly penalizing use of those
# streets:
index <- which (net$access == "private")
net$time_weighted [index] <- net$time_weighted [index] * 100

## End(Not run)

dodgr documentation built on Sept. 11, 2024, 7:52 p.m.