ggplotly() does not render empty plots from qplot() grid

Trying to run a 3x3 qplot() grid through ggplotly()—qplot() renders a fine static plot:

library(plotly)

mtcars$gear <- factor(mtcars$gear,levels=c(3,4,5),
  	labels=c("3gears","4gears","5gears")) 
mtcars$am <- factor(mtcars$am,levels=c(0,1),
  	labels=c("Automatic","Manual")) 
mtcars$cyl <- factor(mtcars$cyl,levels=c(4,6,8),
   labels=c("4cyl","6cyl","8cyl")) 

qplot(hp, mpg, data=mtcars, shape=am, color=am, 
           facets=gear~cyl, size=I(3), 
           xlab="Horsepower", ylab="Miles per Gallon")

But then when run through ggplotly(), the mid-right plot isn't rendered:

ggplotly(qplot(hp, mpg, data=mtcars, shape=am, color=am, 
           facets=gear~cyl, size=I(3), 
           xlab="Horsepower", ylab="Miles per Gallon"))

Is this a bug or expected? Any suggestions on a way to force it to show up?

Thanks.

Reproduisez l’exemple fourni de qplot() et ggplotly() avec les données mtcars et ses facettes 3x3 selon gear et cylinder. Commencez par le chemin de conversion de ggplotly() et comparez les sorties statique et interactive ; le travail est terminé lorsque chaque facette, y compris le panneau vide, s’affiche de manière cohérente ou que le comportement est documenté comme prévu.