Progress bar closes too soon with ggplot - r

Question

I wonder if someone can explain the behavior of the progressBar().
I have trimmed my shiny app to the bare minimum to reproduce this post.
Now to the problem. When I select "AllRuns", the progress bar pops up and then goes away
before the graphic is displayed. But when I select "scatter", the progress bar nicely waits
until the scatter plot is displayed on the main panel. Is this a normal behavior?
How can I make the progress bar wait until the graphic displays when "AllRuns" is selected?
UPDATE The dataset can be read into R from google docs. it takes about 20 seconds to load into R.
library(shiny)
library(tidyverse)
library(DT)
library(data.table)
final <- fread("https://docs.google.com/spreadsheets/d/170235QwbmgQvr0GWmT-8yBsC7Vk6p_dmvYxrZNfsKqk/pub?output=csv")
runs<- c("AllRuns","scatter")
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
selectInput(inputId = "run",
label = "Chinook Runs",
choices = runs,
selected = "AllRuns"),
sliderInput(inputId = "Yearslider",
label="Years to plot",
sep="",
min=2000,
max=2014,
value=c(2010,2012))),
mainPanel(
plotOutput("plot")
)))
server <- function(input, output,session) {
session$onSessionEnded(function() {
stopApp()
})
plot_all <- reactive({
final[final$year >= input$Yearslider[1] & final$year <= input$Yearslider[2], ]
})
plotscatter <- reactive({
rnorm(100000)
})
dataInput <- reactive({
if (input$run == "AllRuns") {
plot_all()
}else{
plotscatter()
}
})
# Plot data
create_plots <- reactive({
withProgress(message="Creating graphic....",value = 0, {
n <- 10
for (i in 1:n) {
incProgress(1/n, detail = input$run)
Sys.sleep(0.1)
}
#Make the plots
theme_set(theme_classic())
switch(input$run,
"AllRuns" = ggplot(plot_all(),aes(SampleDate,Count,color = race2)) +
geom_point() + theme_bw() +
labs(x="",y="Number in thousands",title="All Salmon Runs combined"),
"scatter" = plot(plotscatter(),col="lightblue")
)
})#Progress bar closing brackets
})#create_plots closing brackets
output$plot <- renderPlot({
create_plots()
})
}
# Run the application
shinyApp(ui = ui, server = server)

Answer 1

It is simple that the progress bar is updated by the for-loop and the plot code only run after the for-loop. So the progress-bar reach the end, then plot code started. This kind of progress-bar would work if you are process something along with for-loop for example
list_of_files # assume you have a list of data file to read and process
max_progress <- length(list_of_files)
withProgress(message="Creating graphic....",value = 0, {
for (i in 1:max_progress) {
data <- read_csv(list_of_files[i])
... # doing something here
# once the processing code done next line of code will update the progress bar
incProgress(1/n, detail = input$run)
}
})
If you want to display loading one way to do it is using shinycssloaders::withSpinner() on the UI part which would show an animation of loading while UI is updating by server side.
The withProgress would be more useful when you have a list of items to process.
library(shiny)
library(tidyverse)
library(DT)
library(data.table)
library(shinycssloaders)
final <- fread("https://docs.google.com/spreadsheets/d/170235QwbmgQvr0GWmT-8yBsC7Vk6p_dmvYxrZNfsKqk/pub?output=csv")
runs<- c("AllRuns","scatter")
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
selectInput(inputId = "run",
label = "Chinook Runs",
choices = runs,
selected = "AllRuns"),
sliderInput(inputId = "Yearslider",
label="Years to plot",
sep="",
min=2000,
max=2014,
value=c(2010,2012))),
mainPanel(
withSpinner(plotOutput("plot"))
)))
server <- function(input, output,session) {
session$onSessionEnded(function() {
stopApp()
})
plot_all <- reactive({
final[final$year >= input$Yearslider[1] & final$year <= input$Yearslider[2], ]
})
plotscatter <- reactive({
rnorm(100000)
})
dataInput <- reactive({
if (input$run == "AllRuns") {
plot_all()
}else{
plotscatter()
}
})
# Plot data
create_plots <- reactive({
#Make the plots
theme_set(theme_classic())
switch(input$run,
"AllRuns" = ggplot(plot_all(),aes(SampleDate,Count,color = race2)) +
geom_point() + theme_bw() +
labs(x="",y="Number in thousands",title="All Salmon Runs combined"),
"scatter" = plot(plotscatter(),col="lightblue")
)
})#create_plots closing brackets
output$plot <- renderPlot({
create_plots()
})
}
# Run the application
shinyApp(ui = ui, server = server)