On Wed, 30 Nov 2016, Chris Lusk wrote:

Hello all

I'm making a global map of average leaf size in forests, using different
colours to show dominance of different leaf size classes. The world map is
of course centred on Greenwich (longitude zero) but none of my data are
from Europe or Africa, so a map centred on the Pacific basin would look
much better. In fact I'd like to cut Europe and Africa right out of the map
(nothing personal about this!).

Online I've seen several suggestions for re-centering the map, but they
haven't worked for me. I would really appreciate suggestions about how to
achieve this.

mapdata comes with world2Hires, which is Pacific centred. However, the polygons are not split at 0, so wrap around if you need to fill. I think your xlim= values are incorrect too, I get a Pacific basin from:

map("world2Hires", xlim=c(135, 290), ylim=c(-60,70), lty=1,
 interior=FALSE)

but as lines not filled polygons.

Roger


My map code is pasted in below, and the data can be downloaded at
http://sci.waikato.ac.nz/sites/clusk/DivrepNZ.csv

cheers

Chris
............

library(maps)
library(mapdata)
library(maptools)

###Get world map and fill landmasses to hide national borders
map("worldHires", xlim=c(-165,180),ylim=c(-60,70),lty=1, col="gainsboro",
fill=TRUE, border="gainsboro")

###Show axes with horizontal tick labels
map.axes(cex.axis=0.75, las=1)

###Make axis titles
title(xlab = "Longitude (degrees E)", ylab="Latitude (degrees S)")
##Get site location data to plot

Data = read.csv("DivrepNZ.csv")

Mesophyll = subset (Data, Size == "Mesophyll", select = c("Size", "ID",
"lon", "lat"))
Notophyll = subset (Data, Size == "Notophyll", select = c("Size", "ID",
"lon", "lat"))
Microphyll = subset (Data, Size == "Microphyll", select = c("Size", "ID",
"lon", "lat"))
Nanophyll = subset (Data, Size == "Nanophyll", select = c("Size", "ID",
"lon", "lat"))

points(Mesophyll[,"lon"], Mesophyll[,"lat"],pch=15, cex=0.6, col="red3")
points(Notophyll[,"lon"], Notophyll[,"lat"], pch=15, cex=0.6, col="orange")
points(Microphyll[,"lon"], Microphyll[,"lat"], pch=15, cex=0.6,
col="green3")
points(Nanophyll[,"lon"], Nanophyll[,"lat"], pch=15, cex=0.6, col="blue")




*- - - - - - -*Chris Lusk
Environmental Research Institute
University of Waikato
Hamilton
New Zealand
Senior Editor, *New Zealand Journal of Botany*

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--
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 91 00
e-mail: roger.biv...@nhh.no
http://orcid.org/0000-0003-2392-6140
https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en
http://depsy.org/person/434412

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