How to show a progressBar in a single function in shiny? - r

Question

Here is an example. The progress bar just jumps from 0% to 100% due a single function getres(). How to indicate the progress smoothly?
library("shiny")
library("shinyWidgets")
library("DESeq2")
library("airway")
data(airway)
getres <- function(eset){
dds<-DESeqDataSet(eset, design = ~cell + dex)
keep <- rowSums(counts(dds)) >= 10
dds <- dds[keep,]
dds <- DESeq(dds)
res <- results(dds)
return(res)
}
ui <- fluidPage(
tags$h1("Progress bar in Sweet Alert"),
useSweetAlert(), # /!\ needed with 'progressSweetAlert'
actionButton(
inputId = "go",
label = "Launch long calculation !"
)
)
server <- function(input, output, session) {
observeEvent(input$go, {
progressSweetAlert(
session = session, id = "myprogress",
title = "Work in progress",
display_pct = TRUE, value = 0
)
for (i in seq_len(1)) {
Sys.sleep(0.1)
updateProgressBar(
session = session,
id = "myprogress",
res<-getres(airway),
value = i
)
}
closeSweetAlert(session = session)
sendSweetAlert(
session = session,
title =" Calculation completed !",
type = "success"
)
})
}
shinyApp(ui = ui, server = server)

Answer 1

I was unable to run your example as airway and DESeq2 are not available for R 3.6+. BUT there is an interesting package that I have been meaning to try out called waiter.
Within waiter there is waitress which will "let you display loading bars on the entire screen or specific elements only."
There is a great demo app where you play with the different functions.
Here is an example from the docs!
library(shiny)
library(waiter)
ui <- navbarPage(
"Waitress on nav",
tabPanel(
"home",
use_waitress(),
plotOutput("plot")
)
)
server <- function(input, output){
# now waitress ranges from 0 to 100
waitress <- Waitress$new("nav", theme = "overlay", min = 0, max = 10)
output$plot <- renderPlot({
for(i in 1:10){
waitress$inc(1) # increase by 10%
Sys.sleep(.5)
}
hist(runif(100))
waitress$close() # hide when done
})
}
shinyApp(ui, server)
Hope this helps or gives you other ideas!