[R-sig-Geo] centering map on Pacific Basin instead of Greenwich

[Chris Lusk]

Thanks Roger! After I transform all longitudes to positive values, your
solution works nicely.

Chris


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



On Wed, Nov 30, 2016 at 10:06 PM, Roger Bivand <Roger.Bivand at nhh.no> wrote:

> 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*
>>
>>         [[alternative HTML version deleted]]
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo at r-project.org
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>
>>
> --
> 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.Bivand at nhh.no
> http://orcid.org/0000-0003-2392-6140
> https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en
> http://depsy.org/person/434412
>

	[[alternative HTML version deleted]]