nowrapSpatialLines: Split SpatialLines components at offset

In dis-organization/sp_dplyrexpt: Classes and Methods for Spatial Data

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

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)
nwSL <- nowrapSpatialLines(Sl)
summary(nwSL)

dis-organization/sp_dplyrexpt documentation built on May 15, 2019, 8:52 a.m.