making wrld_simpl longitude borders something other than (-180, 180)
Although, unfortunately, the exact code, but switching "moll" to "latlong",
produces screwups (horizontal lines throughout the plot). Any advice?
Works:
====================
pdffn = "wrld_simpl_moll.pdf"
pdf(file=pdffn, width=12, height=6)
data(wrld_simpl) #The world as a SpatialPolygonsDataFrame
#To avoid the lines crossing the map after reprojection we need to cut the
polygons at the new break:
w <- nowrapRecenter(wrld_simpl, offset = 180-90, avoidGEOS=TRUE)
#Then proceed with the reprojection (note the proj4 string for a mollweide
projection with 150?E as the new center)
wrld_reCentered <- spTransform(w, CRS("+proj=moll +lon_0=-90"))
plot(wrld_reCentered, border="grey", lwd=0.5)
dev.off()
cmdstr = paste0("open ", pdffn)
system(cmdstr)
====================
Produces screwups:
====================
pdffn = "wrld_simpl_latlong.pdf"
pdf(file=pdffn, width=12, height=6)
data(wrld_simpl) #The world as a SpatialPolygonsDataFrame
#To avoid the lines crossing the map after reprojection we need to cut the
polygons at the new break:
w <- nowrapRecenter(wrld_simpl, offset = 180-90, avoidGEOS=TRUE)
#Then proceed with the reprojection (note the proj4 string for a mollweide
projection with 150?E as the new center)
wrld_reCentered <- spTransform(w, CRS("+proj=longlat +lon_0=-90"))
plot(wrld_reCentered, border="grey", lwd=0.5)
dev.off()
cmdstr = paste0("open ", pdffn)
system(cmdstr)
====================
On Mon, Sep 14, 2015 at 4:04 PM, Nick Matzke <matzke at nimbios.org> wrote:
Ah, this did it: http://stackoverflow.com/questions/17718928/how-to-switch-to-a-map-that-is-centered-on-the-china-instead-of-the-default-set (plotting to PDF helps speed it up) library(geosphere) library(gdata) # for read.xls library(maptools) # for e.g. wrld_simpl library(rgdal) library(gpclib) # for polygon clipping pdffn = "wrld_simpl.pdf" pdf(file=pdffn, width=12, height=6) data(wrld_simpl) #The world as a SpatialPolygonsDataFrame #To avoid the lines crossing the map after reprojection we need to cut the polygons at the new break: w <- nowrapRecenter(wrld_simpl, offset = 180-100, avoidGEOS=TRUE) #Then proceed with the reprojection (note the proj4 string for a mollweide projection with 150?E as the new center) wrld_reCentered <- spTransform(w, CRS("+proj=moll +lon_0=-100")) plot(wrld_reCentered, border="grey", lwd=0.5) dev.off() cmdstr = paste0("open ", pdffn) system(cmdstr) On Mon, Sep 14, 2015 at 3:46 PM, Nick Matzke <matzke at nimbios.org> wrote:
Apologies, I got my wires crossed. What I meant was, how would I make a map where the left edge was at longitude 100 (e.g. Thailand), and the right edge is at, say 99 (again Thailand). The Pacific Ocean, and the International Dateline, would be in the middle of this map. I tried the obvious thing: plot(wrld_simpl, xlim = c(100, 99)) ...but that produces a flipped map... Cheers! Nick On Mon, Sep 14, 2015 at 3:38 PM, Frede Aakmann T?gersen <frtog at vestas.com
wrote:
Hi Nick To be honest I do not understand your question so I am guessing that you probably only need to set the xlim to c(-100, 100). Here is an example:
data(wrld_simpl) plot(wrld_simpl) plot(wrld_simpl, xlim = c(-100, 100))
Why would one wants to redefine the longitudes from the interval (-180, 180) to (-100, 100)? Yours sincerely / Med venlig hilsen Frede Aakmann T?gersen Specialist, M.Sc., Ph.D. Plant Performance & Modeling Technology & Service Solutions T +45 9730 5135 M +45 2547 6050 frtog at vestas.com http://www.vestas.com Company reg. name: Vestas Wind Systems A/S This e-mail is subject to our e-mail disclaimer statement. Please refer to www.vestas.com/legal/notice If you have received this e-mail in error please contact the sender. -----Original Message----- From: R-sig-Geo [mailto:r-sig-geo-bounces at r-project.org] On Behalf Of Nick Matzke Sent: 14. september 2015 06:51 To: r-sig-geo at stat.math.ethz.ch Subject: [R-sig-Geo] making wrld_simpl longitude borders something other than (-180, 180) Hi all, I would like to plot wrld_simpl, but have the left and right edges of the map be at something like 100 degrees longitude, rather than (-180, 180). I tried messing with the bounding box with no luck. I can imagine something like burrowing into the object and subtracting 80 degrees from all the longitudes, but I suspect there must be a better way? Any help appreciated! Nick [[alternative HTML version deleted]]
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