r - create reactive filter that is applied to an uploaded csv file in shiny

Question

I'm trying to create a shiny app in which a user would be able to upload a .csv file, and then apply a filter on that dataframe and then make a plot using ggplot2. Unfortunately I stumbled upon a problem when trying to create a select input menu from a variable coming from the .csv that is supposed to be uploaded.

To create a simple example we can export the diamonds dataset from ggplot2 as a .csv file:

write.csv(diamonds, "diamonds.csv")

Then to create the shiny app:

library(shiny)
library(shinyWidgets)
library(ggplot2)

ui <- fluidPage(
    titlePanel("test shiny"),

    # Sidebar with a slider input for number of bins
    sidebarLayout(sidebarPanel(
        fileInput('file1', 'Choose file to upload',
                  accept = c(
                      'text/csv',
                      'text/comma-separated-values',
                      'text/tab-separated-values',
                      'text/plain',
                      '.csv',
                      '.tsv'
                  )
        ),
        tags$hr(),
        pickerInput(
            inputId = "caratx",
            label = "Choose carat",
            choices = c("Select all", unique(user_data$carat)),
            multiple = TRUE
        ),
        selectInput(
            inputId = "clarityx",
            label = "Choose distance: ",
            choices = unique(user_data$clarity)
        )
    ),
    mainPanel(plotOutput("endplot"))
    ))

# Define server logic 
server <- function(input, output) {

    output$endplot <- renderPlot({
        inFile <- input$file1

        if (is.null(inFile))
            return(NULL)

        user_data <- read.csv(inFile$datapath, header = T,
                              sep = ",", quote = input$quote)

        validate(
            need(input$entityx, 'Please select at least one carat'),
            need(input$indicatorx, 'Please select at least one clarity')
        )

        if (input$caratx %in% "Select all") {
            user_data <- user_data %>%
                filter(carat %in% input$caratx)
        } else {
            user_data <- user_data %>%
                filter(carat %in% input$caratx) %>%
                filter(clarity %in% input$clarityx) 
        }

        user_data %>% 
            ggplot(aes(x = `cut`)) +
            geom_point(aes(y = price), color = "red") +
            geom_point(aes(y = depth), color = "blue")
        })
}

# Run the application 
shinyApp(ui = ui, server = server)

This is the output:

Error in unique(user_data$carat) : object 'user_data' not found

Is there a way to make this work ?

Many thanks !

DeanAttali · Accepted Answer

The actual question you're asking should be solved by turning user_data into a reactive and rendering the inputs using uiOutput+renderUI, as @kwiscion correctly commented.

But unfortunately, your code has a few other errors that make it not reproducible:

The sample dataset should be diamonds, not cars
input$quote doesn't exist in your code, so I removed the reference to it
You need to include library(dplyr) for some of the functions in your code
input$entityx and input$indicatorx don't exist

The above 4 errors are not related to your question, but made it much harder and longer to answer your question. In the future, please try to make sure that the code you post is correct and reproducible.

Below is an answer to your question that solved the 4 issues above and implements the two suggestions by @kwiscion

library(shiny)
library(shinyWidgets)
library(ggplot2)
library(dplyr)

ui <- fluidPage(
  titlePanel("test shiny"),

  # Sidebar with a slider input for number of bins
  sidebarLayout(sidebarPanel(
    fileInput('file1', 'Choose file to upload',
              accept = c(
                'text/csv',
                'text/comma-separated-values',
                'text/tab-separated-values',
                'text/plain',
                '.csv',
                '.tsv'
              )
    ),
    tags$hr(),
    uiOutput("caratx_input"),
    uiOutput("clarityx_input")
  ),
  mainPanel(plotOutput("endplot"))
  ))

# Define server logic 
server <- function(input, output) {
  file_data <- reactive({
    req(input$file1)
    read.csv(input$file1$datapath, header = TRUE,
             sep = ",")
  })

  output$caratx_input <- renderUI({
    req(file_data())
    pickerInput(
      inputId = "caratx",
      label = "Choose carat",
      choices = c("Select all", unique(file_data()$carat)),
      multiple = TRUE
    )
  })

  output$clarityx_input <- renderUI({
    req(file_data())
    selectInput(
      inputId = "clarityx",
      label = "Choose distance: ",
      choices = unique(file_data()$clarity)
    )
  })

  output$endplot <- renderPlot({
    req(file_data())

    validate(
      need(input$caratx, 'Please select at least one carat'),
      need(input$clarityx, 'Please select at least one clarity')
    )

    user_data <- file_data()
    if (input$caratx %in% "Select all") {
      user_data <- user_data %>%
        filter(carat %in% input$caratx)
    } else {
      user_data <- user_data %>%
        filter(carat %in% input$caratx) %>%
        filter(clarity %in% input$clarityx) 
    }

    user_data %>% 
      ggplot(aes(x = `cut`)) +
      geom_point(aes(y = price), color = "red") +
      geom_point(aes(y = depth), color = "blue")
  })
}

# Run the application 
shinyApp(ui = ui, server = server)

r - create reactive filter that is applied to an uploaded csv file in shiny

Answers (2)

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