sp (version 0.9-3)

gridlines: Create N-S and E-W grid lines over a geographic region

Description

Create N-S and E-W grid lines over a geographic region; gridat permits the construction of points and labels for non-projected grid annotation

Usage

gridlines(x, easts = pretty(bbox(x)[1,]), norths = pretty(bbox(x)[2,]), ndiscr = 20) 
gridat(x, easts = pretty(bbox(x)[1,]), norths = pretty(bbox(x)[2,]), offset=0.5)

Arguments

x
object deriving from class Spatial-class
easts
numeric; east-west values for vertical lines
norths
numeric; north-south values for horizontal lines
ndiscr
integer; number of points used to discretize the line, could be set to 2, unless the grid is (re)projected
offset
offset value to be returned, see text

Value

  • gridlines returns an object of class SpatialLines-class, with lines as specified; the return object inherits the projection information of x; gridat returns a SpatialPointsDataFrame with points at the west and south ends of the grid lines created by gridlines, with degree labels

See Also

Function spTransform in package rgdal

Examples

Run this code
data(meuse)
coordinates(meuse) = ~x+y
plot(meuse)
plot(gridlines(meuse), add=TRUE)
title("default gridlines within Meuse bounding box")

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