cannot plot negative longitude values in PlotOnStaticMap in R

Question

I have:

> df1
          lon      lat grp
1  0.02310676 51.39729   0
2 -0.04666115 51.40614   0
3  0.09730595 51.38398   0
4  0.02458385 51.39580   1

and want to plot it on a map.

library(RgoogleMaps)
> center
[1] 51.389486  0.036657
mm=GetMap(center=center,zoom=10,maptype= "roadmap", destfile = "satellite.png")
PlotOnStaticMap(mm,lat=df1$lat,lon=df1$lon,pch=20,col=df1$grp, cex=2.3)

the result is 3 correctly placed markers, the missing marker is the one with a negative value. Further examination:

PlotOnStaticMap(mm,lat=51.40614,lon=0.04666115,pch=20,col=c('red','dark blue'), cex=2.3)

shows a red dot where I want it, BUT:

PlotOnStaticMap(mm,lat=51.40614,lon=-0.04666115,pch=20,col=c('red','dark blue'), cex=2.3)

results in nothing.

Any suggestions on how I can include points on the western hemisphere is greatly appreciated!

Answer 1

This seems to be no longer an issue in RgoogleMaps version 1.4.2, which has been released on 2018-06-01:

library(RgoogleMaps)

## example data
df1 = data.frame(lon = c(0.02310676, -0.04666115, 0.09730595, 0.02458385)
                 , lat = c(51.39729, 51.40614, 51.38398, 51.39580)
                 , grp = c("0", "0", "0", "1"))

center = c(51.389486, 0.036657)

## get google map
dfl = tempfile(fileext = ".png")
mm = GetMap(center, zoom = 12, maptype = "roadmap", destfile = dfl)

## display map with points
par(pty = "s")
PlotOnStaticMap(mm, lat = df1$lat, lon = df1$lon, pch = 20, col = df1$grp, cex = 2.3)