Suggest names for a map (experimental)

Features are given a suitability score based on maps prepared by expert cartographers. Data were tabulated from a collection of such maps, indicating for each feature whether it was named on a given map, along with details (such as scale) of the map. These data are used as the basis of a recommendation algorithm, which suggests the best features to name on a map given its properties (extent and scale). This is an experimental function and currently only implemented for map_scale values of 10 million or larger.

Usage

an_suggest(gaz, map_scale, map_extent, map_dimensions)

Arguments

gaz

data.frame or SpatialPointsDataFrame: as returned by an_read, an_preferred, or an_filter

map_scale

numeric: the scale of the map (e.g. 20e6 for a 1:20M map). If map_scale is not provided, it will be estimated from map_extent and map_dimensions

map_extent

vector of c(longitude_min, longitude_max, latitude_min, latitude_max): the extent of the area for which name suggestions are sought. This is required if map_scale is not provided, and optional if map_scale is provided (if map_extent is provided in this situation then the gaz data frame will be filtered to this extent before the suggestion algorithm is applied; otherwise all names in gaz will be considered). map_extent can also be passed as a raster Extent object, a Raster object (in which case its extent will be used), a Spatial object (in which case the bounding box of the object will be used as the extent), or a matrix (in which case it will be assumed to be the output of sp::bbox)

map_dimensions

numeric: 2-element numeric giving width and height of the map, in mm. Not required if map_scale is provided

Value

data.frame of names with a "score" column added. Score values range from 0 to 1. The data frame will be sorted in descending score order. Names with higher scores are those that are suggested as the most suitable for display.

See also

an_read an_thin

Examples

if (FALSE) { # \dontrun{
 g <- an_read(cache = "session")

 ## get a single name per feature, preferring the
 ##  Australian name where there is one
 g <- an_preferred(g, origin = "Australia")

 ## suggested names for a 100x100 mm map covering 60-90E, 70-60S
 ##  (this is about a 1:12M scale map)
 suggested <- an_suggest(g, map_extent = c(60, 90, -70, -60), map_dimensions = c(100, 100))
 head(suggested, 20) ## top 20 names

 ## an equivalent result can be achieved by supplying map scale and extent
 suggested <- an_suggest(g, map_scale = 12e6, map_extent = c(60, 90, -70, -60))
} # }