Mac OS X においてグラフに日本語を表示させるためには、フォントの設定を適切をする必要がある。

.Rprofile に下記設定を追記すると、いい感じで日本語を表示させることができる。

.Rprofile

setHook(packageEvent("grDevices", "onLoad"), function(...){
        if(.Platform$OS.type == "windows")                     
            grDevices::windowsFonts(sans ="MS Gothic",
                                    serif="MS Mincho",           
                                    mono ="FixedFont")
        if(capabilities("aqua"))   
            grDevices::quartzFonts( 
                                   sans =grDevices::quartzFont(  
                                                               c("Hiragino Kaku Gothic Pro W3",
                                                                 "Hiragino Kaku Gothic Pro W6",
                                                                 "Hiragino Kaku Gothic Pro W3",
                                                                 "Hiragino Kaku Gothic Pro W6")),
                                   serif=grDevices::quartzFont( 
                                                               c("Hiragino Mincho Pro W3",
                                                                 "Hiragino Mincho Pro W6",
                                                                 "Hiragino Mincho Pro W3",
                                                                 "Hiragino Mincho Pro W6")))
        if(capabilities("X11"))
            grDevices::X11.options( 
                                   fonts=c("-kochi-gothic-%s-%s-*-*-%d-*-*-*-*-*-*-*",
                                           "-adobe-symbol-medium-r-*-*-%d-*-*-*-*-*-*-*"))
            grDevices::pdf.options(family="Japan1GothicBBB")
            grDevices::ps.options(family="Japan1GothicBBB")})
       
attach(NULL, name = "JapanEnv")
assign("familyset_hook", function() { 
       winfontdevs=c("windows","win.metafile", "png","bmp","jpeg","tiff", "RStudioGD")
       macfontdevs=c("quartz","quartz_off_screen", "RStudioGD")
       devname=strsplit(names(dev.cur()),":")[[1L]][1]
       if ((.Platform$OS.type == "windows") && (devname %in% winfontdevs)) par(family="sans")
       if (capabilities("aqua") && devname %in% macfontdevs) par(family="sans")
}, pos="JapanEnv")
setHook("plot.new", get("familyset_hook", pos="JapanEnv"))
setHook("persp", get("familyset_hook", pos="JapanEnv"))