stop calculation after upload of data until run is clicked again - r

Question

I have a problem with my shinyapp. I want to upload data for my calculations. When I do so the app automatically runs through the whole script the moment the upload is complete, so I implemented an action button. When I start the app and upload the data I have to click on the action button, the program executes and everything works fine. But when I start the app and click on the action Button first and then upload data, the program executes without having to click on the run button again. I made an example here. Because my actual app is ways bigger I need this feature that the programs is not executing automatically after uploading new data once the action button was clicked for the data I uploaded in the first place. I know that there is isolate() and I tried to implement it in every position possible but without any result. Can somebody help me out here?
Here the code. with example data.
Mydata<-data.frame(A=1:1100,B=rnorm(1100, 50, 5))
write.csv(Mydata, file = "MyData.csv")
and the app:
ui <- fluidPage(
titlePanel("Uploading Files"),
sidebarLayout(
sidebarPanel(
fileInput('files1', 'Choose CSV File',
accept=c('text/csv',
'text/comma-separated-values,text/plain',
'.csv'), multiple = TRUE),
tags$hr(),
radioButtons('sep', 'Separator',
c(Comma=',',
Semicolon=';',
Tab='\t'),
','),
actionButton("go","run",class = "btn-primary"),br()
),
mainPanel(tags$head(tags$style(type="text/css", "
#loadmessage {
position: fixed;
top: 95%;
left: 0px;
width: 100%;
padding: 5px 0px 5px 0px;
text-align: center;
font-weight: bold;
font-size: 100%;
color: #000000;
background-color: #CCFF66;
z-index: 105;
}
")),
conditionalPanel(condition="$('html').hasClass('shiny-busy')",
tags$div("Loading...",id="loadmessage")),
verbatimTextOutput('text1')
)
)
)
server <- function(input, output) {
observeEvent(input$go,{
mapz <- reactive({
inFiles <- input$files1
if (is.null(inFiles))
return(NULL)
Q <- read.csv(input$files1[[1, 'datapath']],sep=input$sep,dec="." )
names(Q)<-c("A","B")
Q<-Q[Q$A<1000,]
nom<-seq(round(min(Q$A)),floor(max(Q$A)),by=1)
counts<-matrix(NA,nrow=length(nom),ncol=length(input$files1[,1]))
return(list(as.matrix(nom),counts))
})
output$text1 <-renderPrint(if(is.null(input$files1)==FALSE) as.data.frame(mapz()[[1]]))
})}
shinyApp(ui, server)
Many thanks!

Answer 1

One very quick and effective way you can do this is to make that part of the UI unavailable until the file or files are uploaded. Basically make a uiOutput() call in place of the actionButton() call and move the actionButton() into a renderUI() function in server that has a conditional looking for a not NULL return for mapz(). The button isnt available to be pressed unless there is a non NULL return for mapz(). You should also move the reactive that creates mapz() outside of the observeEvent() so that it becomes usable to the app regardless of whether the button is pressed or not. Now as a caveat this never resets the button so as long as there is a file uploaded the button is pressable. It is functionally the same so the ! operator works like the ==FALSE conditional. Heres the code with the suggested changes :
ui <- fluidPage(
titlePanel("Uploading Files"),
sidebarLayout(
sidebarPanel(
fileInput('files1', 'Choose CSV File',
accept=c('text/csv',
'text/comma-separated-values,text/plain',
'.csv'), multiple = TRUE),
tags$hr(),
radioButtons('sep', 'Separator',
c(Comma=',',
Semicolon=';',
Tab='\t'),
','),
uiOutput("runbutton"),br()
),
mainPanel(tags$head(tags$style(type="text/css", "
#loadmessage {
position: fixed;
top: 95%;
left: 0px;
width: 100%;
padding: 5px 0px 5px 0px;
text-align: center;
font-weight: bold;
font-size: 100%;
color: #000000;
background-color: #CCFF66;
z-index: 105;
}
")),
conditionalPanel(condition="$('html').hasClass('shiny-busy')",
tags$div("Loading...",id="loadmessage")),
verbatimTextOutput('text1')
)
)
)
server <- function(input, output) {
output$runbutton <- renderUI({
if(!is.null(mapz()){
actionButton("go","run",class = "btn-primary")
}
})
mapz <- reactive({
inFiles <- input$files1
if (is.null(inFiles))
return(NULL)
Q <- read.csv(input$files1[[1, 'datapath']],sep=input$sep,dec="." )
names(Q)<-c("A","B")
Q<-Q[Q$A<1000,]
nom<-seq(round(min(Q$A)),floor(max(Q$A)),by=1)
counts<-matrix(NA,nrow=length(nom),ncol=length(input$files1[,1]))
return(list(as.matrix(nom),counts))
})
observeEvent(input$go,{
output$text1 <-renderPrint(if(is.null(mapz())==FALSE) as.data.frame(mapz()[[1]]))
})}
shinyApp(ui, server)

Answer 2

dont know why exactly, but this seems to work:
ui <- fluidPage(
titlePanel("Uploading Files"),
sidebarLayout(
sidebarPanel(
fileInput('files1', 'Choose CSV File',
accept=c('text/csv',
'text/comma-separated-values,text/plain',
'.csv'), multiple = TRUE),
tags$hr(),
radioButtons('sep', 'Separator',
c(Comma=',',
Semicolon=';',
Tab='\t'),
','),
actionButton("go","run",class = "btn-primary"),br()
),
mainPanel(tags$head(tags$style(type="text/css", "
#loadmessage {
position: fixed;
top: 95%;
left: 0px;
width: 100%;
padding: 5px 0px 5px 0px;
text-align: center;
font-weight: bold;
font-size: 100%;
color: #000000;
background-color: #CCFF66;
z-index: 105;
}
")),
conditionalPanel(condition="$('html').hasClass('shiny-busy')",
tags$div("Loading...",id="loadmessage")),
verbatimTextOutput('text1')
)
)
)
server <- function(input, output) {
observeEvent(input$go,{
mapz1 <- reactive({
inFiles <- input$files1
if (is.null(inFiles))
return(NULL)
Q <- read.csv(input$files1[[1, 'datapath']],sep=input$sep,dec="." )
names(Q)<-c("A","B")
Q<-Q[Q$A<1000,]
nom<-seq(round(min(Q$A)),floor(max(Q$A)),by=1)
counts<-matrix(NA,nrow=length(nom),ncol=length(input$files1[,1]))
return(list(as.matrix(nom),counts))
})
mapz<-reactive({isolate(mapz1())})
output$text1 <-renderPrint(as.data.frame(mapz()[[1]]))
})}
shinyApp(ui, server)