SELGEOmap: 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)

Value

GEOmap LIST
STROKESlist
namname of stroke
numnumber of points in stroke
indexindex of stroke
colcolor of stroke
stylestyle of stroke
codecode of stroke
LAT1lower left Lat of stroke
LAT2upper right Lat of stroke
LON1lower left Lon of stroke
LON2upper right Lon of stroke
POINTSlist
latvector of lats
lonvector of lons

Details

Uses splancs 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.

Examples

Run this code

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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