Selecting record date with selectInput in shiny R

Question

I am very new to R programming and I am trying to build an shiny r app that takes in data on shark attack data and builds a bar chart that specifies the frequency of a kind of attack e.g. Provoked, Unprovoked, Boating etc. I want to be able to filter by the region however. Here is a sample of the dataset.

CaseNumber  Year    Type    Country Area            OriginalOrder  Region
1642.00.00  1642    Unprovoked  USA New York        136            Northeast
1779.00.00  1779    Unprovoked  USA Hawaii          152            West
1805.09.00  1805    Invalid     USA New York        160            Northeast
1816.09.03  1816    Unprovoked  USA Rhode Island    164            Northeast
1817.06.24  1817    Unprovoked  USA South Carolina  168            South
1828.00.00  1828    Unprovoked  USA Hawaii          181            West
1830.07.26  1830    Unprovoked  USA Massachusetts   187            Northeast
1837.00.00  1837    Invalid     USA South Carolina  196            South
1837.00.00  1837    Unprovoked  USA South Carolina  197            South

Here is what I have so far with my R code. I am able to have the app show me a bar chart with data for all regions but I'm unsure how to update the app so that for example only attacks that happened in the South show up on the bar chart or only attacks in the Northeast region when selected from the dropdown list of regions while having it default to attacks that happened in all regions.

UI

# Link to Shark Attack Data

setwd("C:\\MyData\\Shark-App");

data <- read.csv("Shark.csv");
attach(data);

#Call in shiny

library(shiny)
library(dplyr);


shinyUI(

  # Use a fluid Bootstrap layout
  fluidPage(
    # Name Page
    titlePanel("Type of Shark attacks by Region"),

    #Generate a row with a sidebar
    sidebarLayout(   

      # Define the sidebar with one input
      sidebarPanel(
        selectInput("Area", "Select your Region:",
                    choices=names(Area)),
        hr(),
        helpText("Data from The Global Shark Attack File ")
      ),

      # Sprcify Bar Plot input
      mainPanel(
        plotOutput("sharkPlot")  
      )

    )
  )
)

Server

# Link to Shark Attack Data

setwd("C:\\MyData\\Shark-App");

data <- read.csv("Shark.csv");
attach(data);

#Check Data for consistency

dim(data);
names(data);

library(shiny)

#Define a server for the Shiny app

shinyServer(function(input, output) {
  # Plot the Shark graph 
  output$sharkPlot <- renderPlot({

    # Render a barplot
    barplot(xtabs(~data$Type),
            space=F, 
            col=rainbow(length(levels(data$Type))),
            main = input$Area,
            ylab= "Number of Attacks",
            xlab= "Type")

  })
})

I appreciate any help I can get

Answer 1

As you are populating the selectInput from your data, you should create the selectInput in your server.R using renderUI & uiOutput

You also need to make your plot reactive based on the selectInput - i.e., so the plot changes when you change your selection. You do this by accessing the value of the selectInput with input$Area

UI

library(shiny)  

shinyUI(

  # Use a fluid Bootstrap layout
  fluidPage(
    # Name Page
    titlePanel("Type of Shark attacks by Region"),

    #Generate a row with a sidebar
    sidebarLayout(   

      # Define the sidebar with one input
      sidebarPanel(
        ## the choices for the selectInput come from the data,
        ## so we've moved this into the server.R
        uiOutput("Area"),
        hr(),
        helpText("Data from The Global Shark Attack File ")
      ),

      # Sprcify Bar Plot input
      mainPanel(
        plotOutput("sharkPlot")  
      )

    )
  )
)

server.R

library(shiny)

#Define a server for the Shiny app

shinyServer(function(input, output) {

  data <- read.csv("Shark.csv");

  ## create selectInput based on the regions of the data
  output$Area <- renderUI({

    choices <- unique(as.character(data$Region))
    selectInput("Area", "Select your Region:", choices=choices)
  })

  # Plot the Shark graph 
  output$sharkPlot <- renderPlot({

    # Render a barplot

    ## filter the data based on the value in `selectInput(Area)`
    data_plot <- data[data$Region == input$Area, ]
    barplot(xtabs(~data_plot$Type),
            space=F, 
            col=rainbow(length(levels(data_plot$Type))),
            main = input$Area,
            ylab= "Number of Attacks",
            xlab= "Type")

  })
})