FileInput Button with selectInput in shiny..! - shiny

Question

I am trying to take the speed variable from the "car" data set which I am uploading to the application. Basically Under select speed: I would like to have all the numbers appearing in the dataset$speed. Under selecInput, the choices should depend upond the data set I am uploading using fileInput. How can I complete this task. For now I have added the choices as 1,2,3. In theory there should be all values of the speed variable of cars data set.
library(shiny)
library(datasets)
##the file I am uploading
data(cars)
dataset=write.csv(cars, "dataset.csv")
ui=fluidPage(
actionButton("upload", "Upload File"),
bsModal("uploadFile", " ", "upload",
sidebarLayout(
sidebarPanel(
fileInput("file","Choose file to upload")
),
mainPanel(
tableOutput("contents")
)
)
),
sidebarLayout(
sidebarPanel(
column(3, selectInput("selectElement", "Select speed:", c(1,2,3),multiple =
T, selectize = F)
)
),
mainPanel(
)
)
)
server=function(input,output,session){
output$contents <- renderTable({
inFile <- input$file
if (is.null(inFile))
return(NULL)
read.csv(inFile$datapath)
})
}
shinyApp(ui,server)

Answer 1

My apologies in advance for a somewhat incomplete response: see below.
First of all, an answer to your query:
If you have a dataset like cars, to identify the "speed" labels you can do:
labls <- unique(cars$speed)
...
selectInput("selectElement", "Select speed:", labls, multiple =
T, selectize = F)
I was hoping to post a complete example, but the current logic (maybe because of the limited code posted?) does not seems right: how can the app a) leave to the user to select which file to use; and at the same time b) already filter for speed?
Of course it is possible that you plan to display datasets that have all a column called "speed", then it would make sense :)
Additionally, but this was not part of your question, you appear to use modal dialogues through the package shinyBS.
Since version 0.14 of shiny (around October 2016) shiny has a very good modal function and personally I think it would be better to use the native function instead.
I thougth to post a simple example derived from your code (but with the selectInput for speed commented out because, as mentioned, it does not appear right in the context of the example posted).
library(shiny)
library(datasets)
data(cars)
dataset = write.csv(cars, "dataset.csv")
labls <- unique(cars$speed) # I left this in the code
ui=fluidPage(
sidebarLayout(
sidebarPanel(
actionButton("upload", "Upload File")
),
mainPanel(tableOutput("contents") )
))
server=function(input,output,session){
# Show modal when button is clicked.
observeEvent(input$upload, {
showModal(dataModal())
})
dataModal <- function(failed = FALSE) {
modalDialog(
fileInput('inputId', label=NULL, multiple = FALSE, accept = NULL, width = NULL, buttonLabel = "Browse...", placeholder = "No file selected")
# , selectInput("selectElement", "Select speed:", labls, multiple =
# T, selectize = F)
)
}
output$contents <- renderTable({
if (length(input$inputId )== 0) return(NULL)
inFile <- input$inputId
# if (is.null(input$selectElement )) return(NULL)
input$inputId
})
}
shinyApp(ui,server)