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connect_highways

Source: R/connect-highways.R
connect_highways.Rd

Takes a list of highways names which must enclose an internal area, and returns a SpatialLines object containing a sequence of OSM nodes which cyclically connect all highways. Will fail if the streets do not form a cycle.

Usage

connect_highways(highways, bbox, plot = FALSE)

Arguments

highways

A vector of highway names passed directly to the Overpass API. Wildcards and whitespaces are `.'; for other options see online help for the overpass API.

bbox

the bounding box for the map. A 2-by-2 matrix of 4 elements with columns of min and max values, and rows of x and y values.

plot

If TRUE, then all OSM data for each highway is plotted and the final cycle overlaid.

Value

A single set of SpatialPoints containing the lat-lon coordinates of the cyclic line connecting all given streets.

Note

  1. connect_highways is primarily intended to provide a means to define boundaries of groups which can then be highlighted using add_osm_groups.

  2. This function can not be guaranteed failsafe owing both to the inherently unpredictable nature of OpenStreetMap, as well as to the unknown relationships between named highways. The plot option enables problematic cases to be examined and hopefully resolved. The function is still experimental, so please help further improvements by reporting any problems!

See also

add_osm_groups.

Other data-extraction: extract_osm_objects(), get_bbox()

Examples

bbox <- get_bbox (c (-0.13, 51.5, -0.11, 51.52))
if (FALSE) { # \dontrun{
highways <- c (
    "Monmouth.St", "Short.?s.Gardens", "Endell.St", "Long.Acre",
    "Upper.Saint.Martin"
)
# Note that dots signify "anything", including whitespace and apostrophes,
# and that '?' denotes optional previous character and so here matches
# both "Shorts Gardens" and "Short's Gardens"
highways1 <- connect_highways (highways = highways, bbox = bbox, plot = TRUE)
highways <- c ("Endell.St", "High.Holborn", "Drury.Lane", "Long.Acre")
highways2 <- connect_highways (highways = highways, bbox = bbox, plot = TRUE)

# Use of 'connect_highways' to highlight a region on a map
map <- osm_basemap (bbox = bbox, bg = "gray20")
# dat_B <- extract_osm_data (key = "building",
#                            value = "!residential",
#                            bbox = bbox)
# Those data are part of 'osmplotr':
dat_BNR <- london$dat_BNR # Non-residential buildings
groups <- list (highways1, highways2)
map <- add_osm_groups (map,
    obj = dat_BNR, groups = groups,
    cols = c ("red", "blue"), bg = "gray40"
)
print_osm_map (map)
} # }