Shiny Dynamic filtering while importing files

Question

Here is an example of dynamic filtering conducted using the iris data frame.

 library(dplyr)
 library(shiny)
 library(purrr)

   make_ui <- function(x, var) {
  if (is.numeric(x)) {
    rng <- range(x, na.rm = TRUE)
    sliderInput(var, var, min = rng[1], max = rng[2], value = rng)
  } else if (is.factor(x)) {
    levs <- levels(x)
    selectInput(var, var, choices = levs, selected = levs, multiple = TRUE)
  } else {
    # Not supported
    NULL
  }
}


filter_var <- function(x, val) {
  if (is.numeric(x)) {
    !is.na(x) & x >= val[1] & x <= val[2]
  } else if (is.factor(x)) {
    x %in% val
  } else {
    # No control, so don't filter
    TRUE
  }
}
 

ui <- fluidPage(
  sidebarLayout(
    sidebarPanel(
      map(names(iris), ~ make_ui(iris[[.x]], .x))
    ),
    mainPanel(
      tableOutput("data")
    )
  )
)
server <- function(input, output, session) {
  selected <- reactive({
    each_var <- map(names(iris), ~ filter_var(iris[[.x]], input[[.x]]))
    reduce(each_var, ~ .x & .y)
  })
  
  output$data <- renderTable(head(iris[selected(), ], 12))
} 
shinyApp(ui, server)

The output looks like this:

How should the code be modified to have a similar output for the time in which we need to import a file, for example, a CSV file using the following code (rather than using a data frame already available):

fileInput('inputFile', 'Choose CSV/XLSX File',
                                             multiple = FALSE,
                                             accept = c('text/csv',
                                                        'text/comma-separated-values',
                                                        'application/vnd.ms-excel',
                                                        'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
                                                        '.csv'))

Here is a code to generate a sample CSV file:

write.csv(iris, "my_example.csv", row.names = F)

How?, In the beginning, in the UI, we need the names of the columns.(map(names(iris), ~ make_ui(iris[[.x]], .x))) — Abbas, Sep 08 '22 at 17:23
My answer [here](https://stackoverflow.com/questions/68584478/how-to-update-shiny-module-with-reactive-dataframe-from-another-module) though written in the context of Shiny modules, should give you the techniques you need. The critical feature is to modify the sidebar every time the source data frame changes. — Limey, Sep 08 '22 at 17:29
I defined reactive values but still have problem with the UI section. Do you mean that I have to modularise it to resolve it? — Abbas, Sep 08 '22 at 17:52

score 1 · Accepted Answer · answered Sep 08 '22 at 18:21

There's no need to modularise. Since you now want part of your UI (the sidebar) to respond dynamically to user input, you can't define that part of the UI in the Ui function. Instead, you need to delegate the population to the server function using uiOutput and renderUI.

I've added a selectInput to the sidebar to allow you to choose either mtcars or iris. Obviously, you should adapt this to satisfy your real use case. This selectInput is used to define a reactive (selectedData) that returns the required dataset. So the other changes simply replace iris with selectedData().

library(dplyr)
library(shiny)
library(purrr)

make_ui <- function(x, var) {
  if (is.numeric(x)) {
    rng <- range(x, na.rm = TRUE)
    sliderInput(var, var, min = rng[1], max = rng[2], value = rng)
  } else if (is.factor(x)) {
    levs <- levels(x)
    selectInput(var, var, choices = levs, selected = levs, multiple = TRUE)
  } else {
    # Not supported
    NULL
  }
}

filter_var <- function(x, val) {
  if (is.numeric(x)) {
    !is.na(x) & x >= val[1] & x <= val[2]
  } else if (is.factor(x)) {
    x %in% val
  } else {
    # No control, so don't filter
    TRUE
  }
}

ui <- fluidPage(
  sidebarLayout(
    sidebarPanel(
      selectInput("sourceData", "Source data:", c("iris", "mtcars")),
      uiOutput("sidebar")
    ),
    mainPanel(
      tableOutput("data")
    )
  )
)
server <- function(input, output, session) {
  selected <- reactive({
    each_var <- map(names(selectedData()), ~ filter_var(selectedData()[[.x]], input[[.x]]))
    reduce(each_var, ~ .x & .y)
  })
  
  selectedData <- reactive({
    if (input$sourceData == "iris") {
      iris
    } else {
      mtcars
    }
  })
  
  output$sidebar <- renderUI({
    map(names(selectedData()), ~ make_ui(selectedData()[[.x]], .x))
  })
  
  output$data <- renderTable(head(selectedData()[selected(), ], 12))
} 

shinyApp(ui, server)

Yes. Of course. Just replace my `selectInput` with a `fileInput` or other widget of your choice and process accordingly. — Limey, Sep 08 '22 at 20:08

Shiny Dynamic filtering while importing files

1 Answers1