dygraphs for indian cities

Indian_cities_temp.R

library(shiny)
library(xts)
library(dygraphs)
library(data.table)

india <- fread("india.csv")

# Define UI for application that draws a histogram
ui <- fluidPage(
   
   # Application title
   titlePanel("Average Temperature of Indian Cities"),
   
   # Sidebar with a slider input for number of bins 
   sidebarLayout(
      sidebarPanel(
         textInput("text", "Enter a City", value = ""),
         submitButton("Submit"),
         br(),
         p("Note:"),
         p("1. Start the city name with capital letter. It is case sensitive. "),
         p("2. Some cities are named as their old name, e.g. Bombay for Mumbai."),
         p("3. Some cities are not in the data. If the city you've entered doesn't
           return any result, please try some other city."),
         p("4. Some months or years might be missing for some cities."),
        p("5. Hover your mouse over the graph to see month, year and temperature"),
        p("6. Drag and select the region in the plot to zoom-in the desired time period. Double click on the plot to zoom-out."),
        hr(),
        p("Data is provided by", a("kaggle", href = "https://www.kaggle.com/berkeleyearth/climate-change-earth-surface-temperature-data", target = "_blank"))
      ),
      
      # Show a plot of the generated distribution
      mainPanel(
         dygraphOutput("dygraph")
      )
   )
)

# Define server logic required to draw a histogram
server <- function(input, output) {
   
  enter_city <- reactive({
    validate(
      need(input$text != "", "Plot will be here when you enter a city")
       )
    
    select_city <- subset(india, City == input$text)
    
    validate(
    need(input$text %in% select_city$City, "City not in the data. Please enter another city.")
    )
    
   select_city[, .(dt, AverageTemperature)]
   xts(select_city$AverageTemperature, as.Date(select_city$dt, format = "%Y-%m-%d"))
  
   })
  
     output$dygraph <- renderDygraph({
     
     dygraph(enter_city(),
             main = paste("Average temperature of", input$text)) %>%
       dyAxis("y", label = "Temp (C)")
     
       })
   
}

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