If you really want to mix base and grid graphics (they don't play nicely together as you have noticed) then you should really use the gridBase package. There is at least one package for doing maps using grid (ggmap or ggMaps or something similar) and there is the regular text function for adding text to a base graph, either of those may be easier than mixing.
Since you are plotting the map after the text, whether the text is visible or not depends on the background drawn for the map, I expect that this differs for the different devices. Would you be surprised if you wrote some text on a piece of paper, then layed a paper map over the top and could not read the paper? If you want the text visible on top of the map, do the text after the map. On Sun, Jun 29, 2014 at 5:56 PM, Spencer Graves <spencer.gra...@structuremonitoring.com> wrote: > I'm confused with the results I'm getting from mixing grid and > traditional graphics. A toy example appears below: The png file created by > gridFn() shows "a label" over Africa, as expected. However, when run > interactively, "a label" appears for roughly half a second, then disappears. > > > Can someone explain these results? > > > Thanks, > Spencer > > > gridFn <- function(){ > pushViewport(plotViewport()) > grid.text(label='a label') > popViewport() > map() > } > > library(grid) > library(maps) > gridFn() > > png('gridTst.png') > gridFn() > dev.off() > > >> sessionInfo() > R version 3.1.0 (2014-04-10) > Platform: i386-w64-mingw32/i386 (32-bit) > > locale: > [1] LC_COLLATE=English_United States.1252 > [2] LC_CTYPE=English_United States.1252 > [3] LC_MONETARY=English_United States.1252 > [4] LC_NUMERIC=C > [5] LC_TIME=English_United States.1252 > > attached base packages: > [1] grid stats graphics grDevices utils datasets methods > [8] base > > other attached packages: > [1] maps_2.3-7 > > loaded via a namespace (and not attached): > [1] tools_3.1.0 >> > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Gregory (Greg) L. Snow Ph.D. 538...@gmail.com ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.