SELGEOmap {GEOmap}

Select parts of a GEOmap

Description

Using area, number of points and Lat-Lon Limits, extracts map strokes and creates a new GEOmap

Usage

SELGEOmap(MAP, ncut = 3, acut = c(0, 1e+05), proj = NULL, LIM = NULL)

Arguments

MAP

Map structure

ncut

minimum number of points in polygon

acut

vector, min and max of areas to include

proj

map projection

LIM

vector, c(lon1, lat1, lon2, lat2)

Details

Uses sf::st_area function. If proj and LIM are NULL then no selection on limits are used ncut is used to eliminate area calculations with strokes less than the specified number.

Value

GEOmap LIST

STROKES

list

nam

name of stroke

num

number of points in stroke

index

index of stroke

col

color of stroke

style

style of stroke

code

code of stroke

LAT1

lower left Lat of stroke

LAT2

upper right Lat of stroke

LON1

lower left Lon of stroke

LON2

upper right Lon of stroke

POINTS

list

lat

vector of lats

lon

vector of lons

Author(s)

Jonathan M. Lees<[e-mail]>

See Also

geoarea, sf::st_area

Examples

library(geomapdata)
data(worldmap)
skam = SELGEOmap(worldmap, ncut=3, acut=c(10000, Inf), proj=NULL, LIM=NULL)

par(mfrow=c(2,1))

#######  plot world map, with all lines:
plotGEOmap(worldmap)
length(worldmap$STROKES$num)
######   same plot with some lines removed:
plotGEOmap(skam)
length(skam$STROKES$num)

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