tmaptools (version 1.2-4)

offset_line: Create a double line or offset line

Description

Create a double line or offset line. The double line can be useful for visualizing two-way tracks or emulating objects such as railway tracks. The offset line can be useful to prevent overlapping of spatial lines.

Usage

offset_line(shp, offset)
double_line(shp, width, sides = "both")

Arguments

shp

SpatialLines(DataFrame)

offset

offset from the original lines

width

width between the left and righthand side

sides

character value that specifies which sides are selected: "both", "left", or "right". The default is "both". For the other two options, see also the shortcut function offset_line.

Examples

# NOT RUN {
if (require(tmap)) {
### Demo to visualise the route of the Amstel Gold Race, a professional cycling race
	tmpdir <- tempdir()
	tmpfile <- tempfile()
	download.file("http://www.gpstracks.nl/routes-fiets/f-limburg-amstel-gold-race-2014.zip",
				  tmpfile, mode="wb")
	unzip(tmpfile, exdir=tmpdir)

	# read GPX file
	AGR <- read_GPX(file.path(tmpdir, "f-limburg-amstel-gold-race-2014.gpx"))

	# read OSM of Zuid-Limburg
	Limburg_OSM <- read_osm(AGR$tracks, ext=1.05)

	# change route part names
	levels(AGR$tracks$name) <- paste(c("First", "Second", "Third", "Final"), "loop")
	AGR$tracks_offset2 <- offset_line(AGR$tracks, offset=c(.0005,0,-.0005,-.001))

	tm_shape(Limburg_OSM) +
		tm_raster(saturation=.25) +
	tm_shape(AGR$tracks_offset2) +
		tm_lines(col = "name", lwd = 4, title.col="Amstel Gold Race", palette="Dark2") +
	tm_shape(AGR$waypoints) +
		tm_bubbles(size=.1, col="gold", border.col = "black") +
		tm_text("name", size = .75, bg.color="white", bg.alpha=.25, auto.placement = .25) +
	tm_legend(position=c("right", "top"), frame=TRUE, bg.color = "gold") +
	tm_view(basemaps = "Esri.WorldTopoMap")

	# TIP: also run the plot in viewing mode, enabled with tmap_mode("view")
}
# }