maptools: nowrapSpatialLines – R documentation

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nowrapSpatialLines

Split SpatialLines components at offset

Description

When recentering a world map, most often from the "Atlantic" view with longitudes with range -180 to 180, to the "pacific" view with longitudes with range 0 to 360, lines crossing the offset (0 for this conversion) get stretched horizonally. This function breaks Line objects at the offset (usually Greenwich), inserting a very small gap, and reassembling the Line objects created as Lines. The rgeos package is required to use this function.

Usage

nowrapSpatialLines(obj, offset = 0, eps = rep(.Machine$double.eps^(1/2.5), 2))

Arguments

`obj`	A Spatial Lines object
`offset`	default 0, untried for other values
`eps`	vector of two fuzz values, both default 2.5 root of double.eps

Value

A Spatial Lines object

Author(s)

Roger Bivand

Examples

Sl <- SpatialLines(list(Lines(list(Line(cbind(sin(seq(-4,4,0.4)),
 seq(1,21,1)))), "1")), proj4string=CRS("+proj=longlat +ellps=WGS84"))
summary(Sl)
if (require(rgeos)) {
nwSL <- nowrapSpatialLines(Sl)
summary(nwSL)
if(require(maps)) {
worldmap <- map("world", plot=FALSE)
worldmapLines <- map2SpatialLines(worldmap, proj4string=CRS("+proj=longlat +datum=WGS84"))
bbox(worldmapLines)
t0 <- nowrapSpatialLines(worldmapLines, offset=180)
bbox(t0)
}
}

maptools

Tools for Handling Spatial Objects

v1.1-1

GPL (>= 2)

Authors

Roger Bivand [cre, aut] (<https://orcid.org/0000-0003-2392-6140>), Nicholas Lewin-Koh [aut], Edzer Pebesma [ctb], Eric Archer [ctb], Adrian Baddeley [ctb], Nick Bearman [ctb], Hans-Jörg Bibiko [ctb], Steven Brey [ctb], Jonathan Callahan [ctb], German Carrillo [ctb], Stéphane Dray [ctb], David Forrest [ctb], Michael Friendly [ctb], Patrick Giraudoux [ctb], Duncan Golicher [ctb], Virgilio Gómez Rubio [ctb], Patrick Hausmann [ctb], Karl Ove Hufthammer [ctb], Thomas Jagger [ctb], Kent Johnson [ctb], Matthew Lewis [ctb] (<https://orcid.org/0000-0003-2244-4078>), Sebastian Luque [ctb], Don MacQueen [ctb], Andrew Niccolai [ctb], Edzer Pebesma [ctb], Oscar Perpiñán Lamigueiro [ctb], Ethan Plunkett [ctb], Ege Rubak [ctb] (<https://orcid.org/0000-0002-6675-533X>), Tom Short [ctb], Greg Snow [ctb], Ben Stabler [ctb], Murray Stokely [ctb], Rolf Turner [ctb]

Initial release

2021-03-14