making wrld_simpl longitude borders something other than (-180, 180)

Hi all,

Thanks for all of the help!  I just wanted to follow-up and post the code
that ended up for my purposes.  (Also, this may help my future self find
the code again in a few years.)

If you want to see the graphic, see: http://phylo.wikidot.com/biogeonick

Cheers, Nick

Code:
=================
#######################################################

# Make a map of Nick Matzke's world travels
#
# Using: http://www.latlong.net/
#
#######################################################

# Plot Great Circle paths:
# https://stat.ethz.ch/pipermail/r-sig-geo/2015-June/023032.html
library(geosphere)
library(gdata)    # for read.xls
library(maptools) # for e.g. wrld_simpl
library(rgdal)      # for e.g.
library(gpclib)   # for polygon clipping
library(fields)      # for colorbar.plot

wd = "/drives/GDrive/Matzke_PhD_docs/CV/_graphics/Matzke_map/"
setwd(wd)

xlsfn = "_Matzke_where_Ive_been_v1.xlsx"
xls = read.xls(xlsfn, header=TRUE, stringsAsFactors=FALSE)
head(xls)
tail(xls)

long_offset = -70

pdffn = "Matzke_map_v1.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+long_offset, avoidGEOS=TRUE)
#Then proceed with the reprojection (note the proj4 string for a
mollweide projection with 150?E as the new center)
CRS_string = paste0("+proj=robin +lon_0=", long_offset)
wrld_reCentered <- spTransform(w, CRS(CRS_string))
#wrld_reCentered2 <- spTransform(wrld_reCentered, CRS("+proj=longlat
+lon_0=90"))

# Color countries by visiting
country_names = setNames(rep("white", length(wrld_simpl$NAME)), wrld_simpl$NAME)
country_colors <- setNames(rep("white", length(wrld_simpl$NAME)),
wrld_simpl$NAME)
countries_visited = c("Germany",
"United States",
"Canada",
"Mexico",
"United Kingdom",
"France",
"Zimbabwe",
"Zambia",
"United Republic of Tanzania",
"Kenya",
"Greece",
"South Africa",
"Namibia",
"Lesotho",
"New Zealand",
"French Guiana",
"Brazil",
"Australia",
"Swaziland",
"Botswana",
"Finland",
"Turkey",
"Angola",
"Madagascar",
"China",
"Spain",
"Chile")

country_colors[countries_visited] = rep("grey70",
times=length(countries_visited))

plot(wrld_reCentered, border="grey40", lwd=0.5, col=country_colors)

xls_original = xls
xls$latitude = jitter(xls$latitude)
xls$longitude = jitter(xls$longitude)

cols_for_lines = rainbow(n=nrow(xls))
for (i in 2:nrow(xls))
    {
    point1 = c(xls$longitude[i-1], xls$latitude[i-1])
    point2 = c(xls$longitude[i], xls$latitude[i])
    names(point1) = c("x","y")
    names(point2) = c("x","y")

    path = gcIntermediate(p1=point1, p2=point2, n=200,
addStartEnd=TRUE, breakAtDateLine=TRUE)

    if (is.null(dim(path)) == FALSE)
        {
        L1 = Line(path)
        Ls1 = Lines(L1, ID="a")
        SL1 = SpatialLines(list(Ls1), proj4string=CRS("+proj=longlat"))
        SL1
        #plot(SL1, add=TRUE)

        lw <- nowrapSpatialLines(SL1, offset = 180+long_offset)
        #Then proceed with the reprojection (note the proj4 string for
a mollweide projection with 150?E as the new center)
        lwrld_reCentered <- spTransform(lw, CRS(CRS_string))
        plot(lwrld_reCentered, add=TRUE, col=cols_for_lines[i], lwd=2)

        #lines(sppoints, col=cols_for_lines[i])
        #path = coordinates(path)
        #sppoints = SpatialPoints(coords=path,
proj4string=CRS("+proj=robin +lon_0=-80"))
        #points(sppoints, col=cols_for_lines[i], add=TRUE)
        }

    if (is.null(dim(path)) == TRUE)
        {
        for (j in 1:length(path))
            {
            path2 = path[[j]]
            #sppoints = SpatialPoints(coords=path2,
proj4string=CRS("+proj=robin +lon_0=-80"))
            #points(sppoints, col=cols_for_lines[i], add=TRUE)
            #lines(sppoints, col=cols_for_lines[i])
            L1 = Line(path2)
            Ls1 = Lines(L1, ID="a")
            SL1 = SpatialLines(list(Ls1), proj4string=CRS("+proj=longlat"))
            SL1
            lw <- nowrapSpatialLines(SL1, offset = 180+long_offset)
            #Then proceed with the reprojection (note the proj4 string
for a mollweide projection with 150?E as the new center)
            lwrld_reCentered <- spTransform(lw, CRS(CRS_string))
            plot(lwrld_reCentered, add=TRUE, col=cols_for_lines[i], lwd=2)
            }
        }
    } # END for (i in 2:nrow(xls))

plot(0,0, pch=".", col="white", xlim=c(0,1), ylim=c(0,1))
stripvals <- ( 1:100)
colorbar.plot(x=0.5, y=0.5, strip=y, horizontal=FALSE)

dev.off()
cmdstr = paste0("open ", pdffn)
system(cmdstr)

=================

On Mon, Sep 14, 2015 at 6:58 PM, englishchristophera at gmail.com <

making wrld_simpl longitude borders something other than (-180, 180)

Thread (2 messages)