How do I connect my inputs to my graph outputs

Question

Apologies if this is a simple question. I have been trying for a while to figure this out and I am still confused. I am building a simple shiny app for my class and still cannot figure out or understand how I connect my inputs to the actual graph output so that when I select something the graph changes.

What I am working on is a basic Plane Crash data set and trying to show how crashes have changed over time etc. Below is my code. I can get the inputs set up and the graph output but I don't know where I'm missing the part that connects the two.


crash_year <- c(2016,2016,2015,2014,2015,2015)
amateur_built <- c('yes','yes','no','no','no','no')
ac_type <- c('Airplane','Airplane,'Airplane,'Helicopter','Airplane','Unknown')

dt <- data.table(crash_year,amateur_built,ac_type)

ui <- fluidPage(


  sidebarLayout(

  sidebarPanel(

    selectInput(inputId = "ac", label = "Aircraft Type:",
                choices = c('Airplane','Helicopter','Glider','Balloon','Unknown','Gyroplane','Weight-Shift','Powered Parachute','Ultralight','Rocket','Gyrocraft','Powered-Lift','Blimp'),
                selected = 'Airplane'),
    selectInput(inputId = 'pro_am', label = "Amateur Built?",
                choices = c('Yes','No'),
                selected = 'Yes')
  ),

  mainPanel(
    plotOutput(outputId = 'bar'),

    dataTableOutput(outputId = 'data'),
    br()
    )
  )
)


server <- function(input, output, session) {


  #create barchart object
  output$bar <- renderPlot({
    ggplot(data = dt, aes(x=crash_year,y=input$ac)) + 
      geom_bar(stat = "identity")
  })

}

shinyApp(ui, server)

my apologies, I put in a sample of the data I am working with — soren thomsen, Apr 05 '19 at 01:13

score 1 · Accepted Answer · answered Apr 05 '19 at 01:36

Below is a working example. Things I edited:

One. Change the pro_am select input choices to be choices = c('yes','no') to match the elements in your data table.

Two. Add reactive to create a reactive object that subsetting your data table based on the inputs. Notice that crash_year is converted factor for plotting.

Third. Change the ggplot code. I am not totally clear what you want to do, but the ggplot code I am using can plot bar chart based on count values.

Four. Add renderDataTable to create the DT output.

library(shiny)
library(ggplot2)
library(data.table)
library(DT)

crash_year <- c(2016,2016,2015,2014,2015,2015)
amateur_built <- c('yes','yes','no','no','no','no')
ac_type <- c('Airplane','Airplane', 'Airplane','Helicopter','Airplane','Unknown')

dt <- data.table(crash_year,amateur_built,ac_type)


ui <- fluidPage(


  sidebarLayout(

    sidebarPanel(

      selectInput(inputId = "ac", label = "Aircraft Type:",
                  choices = c('Airplane','Helicopter','Glider','Balloon','Unknown','Gyroplane','Weight-Shift','Powered Parachute','Ultralight','Rocket','Gyrocraft','Powered-Lift','Blimp'),
                  selected = 'Airplane'),
      selectInput(inputId = 'pro_am', label = "Amateur Built?",
                  choices = c('yes','no'),
                  selected = 'yes')
    ),

    mainPanel(
      plotOutput(outputId = 'bar'),

      dataTableOutput(outputId = 'data'),
      br()
    )
  )
)


server <- function(input, output, session) {

  # Subset dt based on the input
  dt_sub <- reactive({
    dt2 <- dt[, crash_year := factor(crash_year)][amateur_built == input$pro_am & ac_type == input$ac, ]
    return(dt2)
    })

  #create barchart object
  output$bar <- renderPlot({
    ggplot(data = dt_sub(), aes(x = crash_year, fill = ac_type)) + 
      geom_bar(position = "dodge")
  })

  # Output the data table
  output$data <- renderDataTable({
    dt_sub()
  })
}

shinyApp(ui, server)

How do I connect my inputs to my graph outputs

1 Answers1

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