How to wrap the reactive elements inside a progress bar(Graphic) - r

Question

I have .txt file and .xlsx file which will be uploaded into shiny.
The .txt upload is fine, the builtin progress bar shows perfect progress.
But in the case of .xlsx file upload I have merging operation doing inside reactive element so it is not coinciding with the actual progress. (Progress bar always finishes ahead of the task)
I can use pbapply, but then again I have to monitor them through command line, this is not what I am looking for.
I am very much interested in making the built in progress bar in connection with the entire upload process inside the reactive element. How can I do that.
This is my program.
ui.R
shinyUI(fluidPage(
titlePanel("Uploading Files"),
sidebarLayout(
sidebarPanel(
fileInput('file1', 'Choose first file to upload',
accept = c(
'text/csv',
)
),))sidebarLayout(
sidebarPanel(
fileInput('file1', 'Choose second file to upload',
accept = c(
'.xlsx'
)
)
)))
server.R
shinyServer(function(input, output) {
a <- reactive({
fileinput1 <- input$file1
if (is.null(fileinput1))
return(NULL)
read.table(fileinput1$datapath, header = TRUE, col.names = c("Experiment","Mesocosm","Hour","Nphy","Cphy","CHLphy","Nhet","Chet","Ndet","Cdet","DON","DOC","DIN","DIC","AT","dCCHO","TEPC","Ncocco","Ccocco","CHLcocco","PICcocco","PAR","Temperature","Salinity","CO2atm","u10","DICflux","CO2ppm","CO2mol","pH"))
#a$Chla <- a$CHLphy + a$CHLcocco #Add new columns as per observation data
#a$PON <- a$Nphy + a$Nhet + a$Ndet + a$Ncocco
})
#Upload Observation Data
b <- reactive({
#xlfile <- list.files(pattern = "*.xlsx")
fileinput2 <- input$file2
if (is.null(fileinput2))
return(NULL)
xlfile <- fileinput2$datapath
wb <- loadWorkbook(xlfile)
sheet_ct <- wb$getNumberOfSheets()
for( i in 1:sheet_ct) { #read the sheets into 3 separate dataframes (mydf_1, mydf_2, mydf3)
print(i)
variable_name <- sprintf('mydf_%s',i)
assign(variable_name, read.xlsx(xlfile, sheetIndex=i))
}
colnames(mydf_1) <- names(mydf_3)
colnames(mydf_2) <- names(mydf_3)
full_data <- rbind(mydf_1[-1,],mydf_2[-1,],mydf_3[-1,]) #making one dataframe here
b <- lapply(full_data,function(x) as.numeric(x))
})
})
How can I achieve this ?

Answer 1

You have some problems in your code but in theory you can create progress bar to the top of the browser:
observe({
fileinput2 <- input$file2
if (is.null(fileinput2))
return(NULL)
withProgress(message = 'Downloading file', value = 0, {
#xlfile <- list.files(pattern = "*.xlsx")
xlfile <- fileinput2$datapath
wb <- loadWorkbook(xlfile)
sheet_ct <- wb$getNumberOfSheets() # this will be used in progressbar
for( i in 1:sheet_ct) { #read the sheets into 3 separate dataframes (mydf_1, mydf_2, mydf3)
print(i)
variable_name <- sprintf('mydf_%s',i)
assign(variable_name, read.xlsx(xlfile, sheetIndex=i))
incProgress(1/sheet_ct, detail = paste("Sheet:", sheet_ct,"Dowloaded"))
}
colnames(mydf_1) <- names(mydf_3)
colnames(mydf_2) <- names(mydf_3)
full_data <- rbind(mydf_1[-1,],mydf_2[-1,],mydf_3[-1,]) #making one dataframe here
b <- lapply(full_data,function(x) as.numeric(x))
})
})
})
More info: http://shiny.rstudio.com/articles/progress.html