1

I am trying to create multiple plots in the same shiny window. Not sure what I am doing wrong. It throws an error that something is up with my main panel.

I tried a few different things but nothing seems to work. Btw this is an adaptation of Mike's answer to this question How can put multiple plots side-by-side in shiny r?

library(ggplot2)
library(gridExtra)
library(shiny)

ui <- fluidPage(
  titlePanel("title panel"),
  sidebarLayout(position = "left",
                sidebarPanel("sidebar panel",
  checkboxInput("donum1", "plot1", value = T),
  checkboxInput("donum2", "plot2", value = F),
  checkboxInput("donum3", "plot3", value = F)
),
  mainPanel("main panel", outputplot="myPlot")))

server <- function(input, output, session) {
  
  Feature_A <- c(1, 2,1, 4,2)
  Feature_B <- c(4,5,6,6,6)
  Feature_C <- c(22,4,3,1,5)
  df<- data.frame(Feature_A ,Feature_B ,Feature_C)
  
  pt1 <- reactive({
    if (!input$donum1) return(NULL)
  p1<-ggplot(data=df, aes(Feature_A))+ geom_histogram()
  })
  pt2 <- reactive({
    if (!input$donum2) return(NULL)
  p2<-ggplot(data=df, aes(Feature_B))+ geom_histogram()
  })
  pt3 <- reactive({
    if (!input$donum3) return(NULL)
  p3<-ggplot(data=df, aes(Feature_C))+ geom_histogram()
  })
  
  output$myPlot = renderPlot({
    grid.arrange(p1, p2, p3, ncol=2,top="Main Title")
  })
  
}

shinyApp(ui, server)

EDIT:

Thanks to YBS's comment below, I have been able to figure out the above issue and have made the change to my code above. But the code is not generating any plot. Can someone help please!

freshman_2021
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1 Answers1

2

That mainPanel() call wasn't nested correctly. It needed a comma before it, because it's an argument to sidebarLayout() (which in turn is an argument to fluidPage().

ui <- fluidPage(
  titlePanel("title panel"),
  sidebarLayout(
    position = "left",
    sidebarPanel(
      "sidebar panel",
      checkboxInput("donum1", "plot1", value = T),
      checkboxInput("donum2", "plot2", value = F),
      checkboxInput("donum3", "plot3", value = F)
    ),
    mainPanel("main panel", outputplot="myPlot")
  )
)

I like using the indention/tab level to show the nested structure more clearly. It helps me catch my mistakes.

After your second question:

I'm not sure how far you want to take it towards the example you gave. The most important difference I see is that you're not returning anything from pt1, pt2, & pt3. Remove the assignment part (e.g., p1<-).

server <- function(input, output, session) {
  Feature_A <- c(1, 2,1, 4,2)
  Feature_B <- c(4,5,6,6,6)
  Feature_C <- c(22,4,3,1,5)
  df<- data.frame(Feature_A ,Feature_B ,Feature_C)
  
  pt1 <- reactive({
    if (!input$donum1) return(NULL)
    ggplot(data=df, aes(Feature_A))+ geom_histogram()
  })
  pt2 <- reactive({
    if (!input$donum2) return(NULL)
    ggplot(data=df, aes(Feature_B))+ geom_histogram()
  })
  pt3 <- reactive({
    if (!input$donum3) return(NULL)
    ggplot(data=df, aes(Feature_C))+ geom_histogram()
  })
  
  output$myPlot = renderPlot({
    ptlist <- list(pt1(),pt2(),pt3())
    wtlist <- c(input$wt1,input$wt2,input$wt3)
    # remove the null plots from ptlist and wtlist
    to_delete <- !sapply(ptlist,is.null)
    ptlist <- ptlist[to_delete] 
    wtlist <- wtlist[to_delete]
    if (length(ptlist)==0) return(NULL)

    grid.arrange(grobs=ptlist,widths=wtlist,ncol=length(ptlist))
  })
  
}
wibeasley
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