[R-sig-Geo] Plot coordinates on world map with Robinson CRS - ggplot2

[Roger Bivand]

On Mon, 18 Feb 2019, Miluji Sb wrote:

> Dear all,
>
> I am trying to plot coordinates on a world map with Robinson CRS. While the
> world map is generated without any issues, when I try to plot the points -
> I only get a single point.

Well, the point is correct, since you didn't project df, did you? This 
seems to be typical of the arcane nature of ggplot invocations. Did you 
try tmap? Almost all the loaded&attached packages are superfluous too.

Roger

>
> The code I am using and the coordinates data is below. What am I doing
> wrong? Any help/suggestions will be highly appreciated.
>
> library(data.table)
> library(foreign)
> library(readstata13)
> library(rgdal)
> library(maptools)
> library(ggplot2)
> library(dplyr)
>
> load(url("
> https://github.com/valentinitnelav/RandomScripts/blob/master/NaturalEarth.RData?raw=true
> "))
>
> PROJ <- "+proj=robin +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84
> +units=m +no_defs"
>
> NE_countries_rob  <- spTransform(NE_countries, CRSobj = PROJ)
> NE_graticules_rob <- spTransform(NE_graticules, CRSobj = PROJ)
> NE_box_rob        <- spTransform(NE_box, CRSobj = PROJ)
>
> # project long-lat coordinates for graticule label data frames
> # (two extra columns with projected XY are created)
> prj.coord <- project(cbind(lbl.Y$lon, lbl.Y$lat), proj=PROJ)
> lbl.Y.prj <- cbind(prj.coord, lbl.Y)
> names(lbl.Y.prj)[1:2] <- c("X.prj","Y.prj")
>
> prj.coord <- project(cbind(lbl.X$lon, lbl.X$lat), proj=PROJ)
> lbl.X.prj <- cbind(prj.coord, lbl.X)
> names(lbl.X.prj)[1:2] <- c("X.prj","Y.prj")
>
> m <- ggplot() +
>  # add Natural Earth countries projected to Robinson, give black border
> and fill with gray
>  geom_polygon(data=NE_countries_rob, aes(long,lat, group=group),
> colour="black", fill="gray80", size = 0.25) +
>  # Note: "Regions defined for each Polygons" warning has to do with
> fortify transformation. Might get deprecated in future!
>  # alternatively, use use map_data(NE_countries) to transform to data
> frame and then use project() to change to desired projection.
>  # add Natural Earth box projected to Robinson
>  geom_polygon(data=NE_box_rob, aes(x=long, y=lat), colour="black",
> fill="transparent", size = 0.25) +
>  # add graticules projected to Robinson
>  geom_path(data=NE_graticules_rob, aes(long, lat, group=group),
> linetype="dotted", color="grey50", size = 0.25) +
>  # add graticule labels - latitude and longitude
>  geom_text(data = lbl.Y.prj, aes(x = X.prj, y = Y.prj, label = lbl),
> color="grey50", size=2) +
>  geom_text(data = lbl.X.prj, aes(x = X.prj, y = Y.prj, label = lbl),
> color="grey50", size=2) +
>  # the default, ratio = 1 in coord_fixed ensures that one unit on the
> x-axis is the same length as one unit on the y-axis
>  coord_fixed(ratio = 1) +
>  geom_point(data=df,
>             aes(x=lon, y=lat), colour="Deep Pink",
>             fill="Pink",pch=21, size=2, alpha=I(0.7))
>  # remove the background and default gridlines
>  theme_void()
>
> ## coordinates dataframe
> dput(df)
> structure(list(lon = c(2.67569724621467, 17.5766416259819,
> 28.4126232192772,
> 23.8147674538232, 29.8917589327105), lat = c(28.1503115976162,
> -12.3388787380201, 9.78891068739477, -22.1873831176644, -3.36546931479253
> )), class = "data.frame", row.names = c(NA, -5L))
>
> Sincerely,
>
> Milu
>
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>
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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; e-mail: Roger.Bivand using nhh.no
https://orcid.org/0000-0003-2392-6140
https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en