Why the histogram doesn't work – shiny library in R

Dataset: https://www.kaggle.com/mirichoi0218/insurance

Hi, I have a problem with shiny library. Wanted to create app that will show the Charges depending on the age, region and children. Unfortunately, the histogram doesn’t work.

ui <- fluidPage(
  titlePanel("Insurance charges"),
  sidebarLayout(
    sidebarPanel(
      sliderInput("ageInput", "Age", 18, 64, 41),
      radioButtons("childrenInput", "Liczba dzieci",
                   choices = c("0", "1", "2", "3",'4','5'),
                   selected = "0"),
      selectInput("regionInput", "Region",
                  choices = c("NE", "NW", "SE","SW"))
    ),
    mainPanel(
      plotOutput("coolplot"),
      br(), br(),
      tableOutput("results")
    )
  )
)

server <- function(input, output) {
  output$coolplot <- renderPlot({
    filtered <-
      insurance %>%
      filter(age >= input$ageInput[1],
             age <= input$ageInput[2],
             children == input$childrenInput,
             region == input$regionInput
      )
    ggplot(filtered, aes(insurance$charges)) +
      geom_histogram()
  })
}

shinyApp(ui = ui, server = server)

>Solution :

The major issue with your code is that

• you map insurance$charges on x in ggplot(). That’s why you always get a histogram for the total dataset. Simply use aes(charges) to use the column from your filtered dataset.

• Not sure about that. Maybe your recoded your data, but the regions in the Kaggle dataset have labels "northeast", "northwest", …. To account for that you could use a named vector for the choices in the selectInput

• Finally, you have to use a vector of length 2 for the value of the sliderInput to get a range slider.

And as an example on how to provide a minimal reproducible example I used a random fake dataset for the reprex.

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

ui <- fluidPage(
  titlePanel("Insurance charges"),
  sidebarLayout(
    sidebarPanel(
      sliderInput("ageInput", "Age", min = 18, max = 64, value = c(18, 41)),
      radioButtons("childrenInput", "Liczba dzieci",
        choices = c("0", "1", "2", "3", "4", "5"),
        selected = "0"
      ),
      selectInput("regionInput", "Region",
        choices = c("NE" = "northeast", "NW" = "northwest", "SE" = "southeast", "SW" = "southwest")
      )
    ),
    mainPanel(
      plotOutput("coolplot"),
      br(), br(),
      tableOutput("results")
    )
  )
)

server <- function(input, output) {
  output$coolplot <- renderPlot({
    filtered <- insurance %>%
      filter(
        age >= input$ageInput[1],
        age <= input$ageInput[2],
        children == input$childrenInput,
        region == input$regionInput
      )

    ggplot(filtered, aes(charges)) +
      geom_histogram()
  })
}

shinyApp(ui = ui, server = server)

DATA

set.seed(123)

insurance <- data.frame(
  age = sample(18:64, 1000, replace = TRUE),
  children = sample(0:5, 1000, replace = TRUE),
  region = sample(c("southwest", "southeast", "northwest", "northeast"), 1000, replace = TRUE),
  charges = runif(1000, 3000, 40000)
)