SELGEOmap: Select parts of a GEOmap

In GEOmap: Topographic and Geologic Mapping

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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GEOmap documentation built on Sept. 11, 2024, 7:57 p.m.