sp (version 0.9-4)

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. A similar function for polygons is found in the spgpc package.

Usage

nowrapSpatialLines(obj, offset = 0, eps = rep(.Machine$double.eps, 2))

Arguments

obj

A Spatial Lines object

offset

default 0, untried for other values

eps

vector of two fuzz values, both default double.eps

Value

• A Spatial Lines object

Examples

Sl <- SpatialLines(list(Lines(list(Line(cbind(sin(seq(-4,4,0.4)), seq(1,21,1)))))), proj4string=CRS("+proj=longlat"))
summary(Sl)
#lapply(sapply(getSLlinesSlot(Sl), getLinesLinesSlot), bbox)
#lapply(sapply(getSLlinesSlot(recenter(Sl)), getLinesLinesSlot), bbox)
nwSL <- nowrapSpatialLines(Sl)
summary(nwSL)
#lapply(sapply(getSLlinesSlot(nwSL), getLinesLinesSlot), bbox)
#lapply(sapply(getSLlinesSlot(recenter(nwSL)), getLinesLinesSlot), bbox)