maptools: holepolys – R documentation

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holepolys

Hisaji Ono's lake/hole problem

Description

How to plot polygons with holes - holes are encoded by coordinates going anticlockwise, and overplotting is avoided by re-ordering the order in which polygons are plotted.

This example is retained for historical interest only, other solutions are present in the sp package.

Usage

data(gpcholes)

Details

"Date: Tue, 11 May 2004 12:54:20 +0900 From: Hisaji ONO To: r-help

I've tried to create a polygon with one hole by gpclib using following example script.

holepoly <- read.polyfile(system.file("poly-ex/hole-poly.txt", package="gpclib"), nohole = FALSE) area.poly(holepoly) plot(holepoly,poly.args=list(col="red",border="blue"))

And I noticed plot function couldn't draw polygons with holes correctly.

Does anyone know how to solve this situation?"

*(h1pl has reversed the y component of polygon 1, to make its ring direction clockwise, h2pl reverses the order of the two polygons in holepoly1@pts)*

Source

Data file included in "gpclib" package.

Examples

data(gpcholes)
opar <- par(mfrow=c(1,2))
plot(SpatialPolygons(list(h2pl)), col="red", pbg="white", border="blue")
plot(SpatialPolygons(list(h1pl)), col="red", pbg="white", border="blue")
par(opar)

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