CODEWITHSUNDEEP
rggplot2shiny
tumultous_rooster
tumultous_rooster

Reputation: 12550

Create a number of renderPlot functions, based on the number of plots I have in a list of ggplots?

Is there any way I can dynamically create a number of renderPlot functions, based on the number of plots I have in a list of ggplots?

I have a Shiny app where instead of having a stable UI, and instead of using renderUI, I am relying on a user-supplied config file to tell Shiny how many plots to show. The config file also supplies data and pretty much helps do most of the heavy lifting.

After much battling, I'm mostly there. With the handy-dandy config file, I can build the correct UI, and generate the correct number of ggplots. The ggplots live in a list, creatively named list_of_ggplots.

But now, I'm at a point where I have a list of ggplots, and I need to allow them to be plotted by using them like this: 

  output$plot1 <- renderPlot({
  print(list_of_ggplots[[1]])
})

But now I have an existentialist crisis -- I can't do it like this, since the user-supplied config file tells me how many plots I have. I can no longer hard code the renderPlot call like is usually done in Shiny, since the number of these functions needed is defined in the config file.

Given my list of ggplots, I need some way to generate the renderPlot calls.

Has anyone done this or have any ideas? Much appreciated.

Here's my code:

SERVER.R:

library(shiny)
library(ggplot2)

# 3 simple plots of different colors -- used here instead of all the complicated stuff
# where someone uses the config file that specified 3 plots, with data, etc.

ggplot_names <- c("p1", "p2", "p3")
ggplot_colors <- c("red", "blue", "green")
list_of_ggplots <- list()
j = 1
for (i in ggplot_names){
  i <- ggplot(data.frame(x = c(-3, 3)))         
  i <- i + aes(x)
  i <- i + stat_function(fun = dnorm, colour=ggplot_colors[[j]])
  list_of_ggplots[[j]] <- i
  j <- j+ 1
}

## here's the problem -- the user specified 3 plots. 
## I can't hardcode the following shinyServer functions!!!
## What if tomorrow, the user specifies 2 plots instead?
shinyServer(function(input, output) { 

  output$plot1 <- renderPlot({
  print(list_of_ggplots[[1]])
})

  output$plot2 <- renderPlot({
  print(list_of_ggplots[[2]])
})

  output$plot3 <- renderPlot({
  print(list_of_ggplots[[3]])
})
})

UI.R

## this top part is actually sourced from the config file
## since Shiny needs to know how many tabPages to use,
## names for the tabs, etc

number_of_tabPages <- 3
tab_names <- c("", "Tab1", "Tab2", "Tab3")
tabs<-list()
tabs[[1]]=""
for (i in 2:(number_of_tabPages+1)){
  tabs[[i]]=tabPanel(tab_names[i],plotOutput(paste0("plot",i-1)))}

## Here's the familiar UI part
shinyUI(fluidRow(

        column(12,
               "", 
               do.call(navbarPage,tabs)
              ) 
                )
      )

Upvotes: 3

Views: 577

Answers (1)

Marat Talipov
Marat Talipov

Reputation: 13304

You can use this solution (I modified only the shinyServer part of your scripts, so I don't list the repeating code here):

 shinyServer(function(input, output) {

 observe(
     lapply(seq(3),function(i) output[[paste0("plot",i)]] <- renderPlot(list_of_ggplots[[i]]))
 )

 })

Of course, you can replace 3 by a variable.

Upvotes: 1

Related Questions