In R shiny app, how to plot two ggplot objects arranged by “arrangeGrob()”?

[Yaohui Zeng]

Dear R-Shiny users,

I have a plot which consists of ggplot objects and is arranged by following code:

## ggplot shared legend
grid_arrange_shared_legend <- function(..., position = c("bottom", "right")) {
 
  plots <- list(...)
  position <- match.arg(position)
  g <- ggplotGrob(plots[[1]] + theme(legend.position=position))$grobs
  legend <- g[[which(sapply(g, function(x) x$name) == "guide-box")]]
  lheight <- sum(legend$height)
  lwidth <- sum(legend$width)
  gl <- lapply(plots, function(x) x + theme(legend.position="none"))
 
  combined <- switch(position,
                     "bottom" = arrangeGrob(do.call(arrangeGrob, gl),
                                            legend,
                                            ncol = 1,
                                            heights = unit.c(unit(1, "npc") - lheight, lheight)),
                     "right" = arrangeGrob(do.call(arrangeGrob, gl),
                                           legend,
                                           ncol = 2,
                                           widths = unit.c(unit(1, "npc") - lwidth, lwidth)))
#   combined
  grid.draw(combined)
}

It works nicely in general. However, it doesn't work in a Shiny App with renderPlot() like following:

  output$main.plot <- renderPlot({

    fit <- res$main.fit
 
    # p1, p2 are two ggplot objects. It works fine if I just plot only one.
    p1 <- get_ggplot(fit)
    p2 <- get_ggplot(fit)

    grid_arrange_shared_legend(p1, p2)

  })

Could anyone clarify to me what the problem is and how I can fix it? Thank you very much!

Yaohui

[Robin Cura]

Hi,

I thought it had something to do with grid.draw being called in a function, but just tried it and it works, see this example : https://gist.github.com/RCura/2e92f7659a37c0aad9b95cd210fa517e

So, I think your error is with your plots p1 and p2 :)

HTH,

Robin

Robin Cura

Doctorant à l'UMR Géographie-cités

LabEx DynamiTe & Université Paris 1 Panthéon-Sorbonne

--
You received this message because you are subscribed to the Google Groups "Shiny - Web Framework for R" group.
To unsubscribe from this group and stop receiving emails from it, send an email to shiny-discus...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/shiny-discuss/49a14b3a-a0c2-4d10-a529-98ec6bac2c2f%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Yaohui Zeng]

​Thank you, Robin. It worked out!