show an unknown number of graphs in a grid RShiny - r

Question

I have looked at all the solutions on SO using grid.arrange but it doesn't really achieve what I want.
Let's assume I have a list of grobs that are generated within a reactive environment in RShiny.
I would like to create a mainPanel where those graphs are on 2 columns (until that point, it's all feasible with grid.arrange) but where each line corresponds to a fluidRow element.
A barebone example of this would be
ui <- fluidPage(
titlePanel("TEST"),
sidebarPanel(width=3,
actionButton(inputId = 'launchCalcButton',label = 'Launch Calc')
),
mainPanel(
uiOutput("resultsPlotUI")
)
)
server <- function(input,output){
graphsList <- eventReactive(input$launchCalcButton, {
a <- lapply(1:10,function(i){
return(
ggplot(data = data.frame(a=rnorm(10),b=rnorm(10)),aes(x=a,y=b))
+geom_point()
)
})
return(a)
})
output$resultsPlot <- renderPlot({
do.call(grid.arrange,c(graphsList(),ncol=2))
})
output$resultsPlotUI <- renderUI({
fluidRow(
column(12,
plotOutput(
outputId = 'resultsPlot'
)
)
)
})
}
app = shinyApp(ui,server)
runApp(app)
All the graphs end up squeezed into one single line whereas I would want them to be split between lines.

Answer 1

You just need to set up height parameter for the plotOutput:
library(shiny)
library(gridExtra)
ui <- fluidPage(
titlePanel("TEST"),
sidebarPanel(width=3,
actionButton(inputId = 'launchCalcButton',label = 'Launch Calc')
),
mainPanel(
uiOutput("resultsPlotUI")
)
)
server <- function(input,output){
graphsList <- eventReactive(input$launchCalcButton, {
a <- lapply(1:10,function(i){
return(
ggplot(data = data.frame(a=rnorm(10),b=rnorm(10)),aes(x=a,y=b))
+geom_point()
)
})
return(a)
})
output$resultsPlot <- renderPlot({
l <- length(graphsList())/2
print(l)
do.call(grid.arrange,c(graphsList(),ncol=2))
})
output$resultsPlotUI <- renderUI({
fluidRow(
column(12,
plotOutput(
outputId = 'resultsPlot', height = 600
)
)
)
})
}
app = shinyApp(ui,server)
runApp(app)
Exactly in this place:
output$resultsPlotUI <- renderUI({
fluidRow(
column(12,
plotOutput(
outputId = 'resultsPlot', height = 600
)
)
)
})
I have set it up to 600 px (height = 600) but you can choose whatever you want.