nowrapSpatialLines

0th

Percentile

Split SpatialLines components at offset

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.

Keywords
spatial
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

See Also

recenter-methods, nowrapSpatialPolygons

Aliases
  • nowrapSpatialLines
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)
nwSL <- nowrapSpatialLines(Sl)
summary(nwSL)
if(require(maps)) {
worldmap <- map("world", plot=FALSE)
worldmapLines <- map2SpatialLines(worldmap, proj4string=CRS("+proj=longlat +datum=WGS84"))
bbox(worldmapLines)
if (require(rgeos)) {
t0 <- nowrapSpatialLines(worldmapLines, offset=180)
bbox(t0)
}
}
Documentation reproduced from package maptools, version 0.8-37, License: GPL (>= 2)

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