R Shiny，Leaflet-> SelectInput在下拉菜单中更改选择的问题

您已经完成了所有必要的工作。只需将所有硬编码的意大利替换为数据，即可将机场数据的子集替换为用户选择的国家/地区。我也考虑将其移动selectInput到仪表板的顶部，因为很难从底部滚动它，并且用户可能看不到它。我将其放在顶部居中，以避免下拉选项被放大控件覆盖。

更新的代码：

#----------Loading my data----------#
#Dataset 1: Routes
routes=read.csv(url("https://raw.githubusercontent.com/jpatokal/openflights/master/data/routes.dat"))


#Dataset #2: Airports
airports=read.csv(url("https://raw.githubusercontent.com/jpatokal/openflights/master/data/airports-extended.dat"))


#Give Better Names to Columns

colnames(routes)=c("Airline","AirlineID","IATA","SourceAP_ID","DestinationAirport","DestAP_ID","Codeshare","Stops","Equipment")

colnames(airports)=c("AirportID","Name","City","Country","IATA","ICAO","Latitude","Longitude","Altitude","Timezone","DST","TzDatabaseTz","Type","Source")

#Join datasets on Source Airport

fullair=merge(x=routes,y=airports,by="IATA",all.x=TRUE)


#----------Preprocessing Data---------#
fullair2=subset(fullair,fullair$Type=="airport")

fullair2$UniqueID=paste0(fullair2$IATA,"_",fullair2$DestinationAirport)

library(dplyr)

fullair3 = fullair2 %>%
  group_by(IATA) %>%
  mutate(Count=n_distinct(UniqueID)) %>%
  ungroup()

fullair3=as.data.frame(fullair3)


fullair3=fullair3[!duplicated(fullair3[c("UniqueID")]),]

library(rowr)
library(sqldf)
library(RSQLite)



library(stringi)
fullair3$Region=stri_extract(fullair3$TzDatabaseTz, regex='[^/]*')

SpitOutNum=sqldf("select IATA,count(*)
                      from fullair3
                      group by IATA")

# SpitOutNum=as.data.frame(SpitOutNum3)

colnames(SpitOutNum)=c("IATA","DestinationCount")
fullair3=merge(x=fullair3,y=SpitOutNum,by="IATA",all.x=TRUE)

#Create the full name
fullair3$NamePart1=paste("(",fullair3$IATA,")",sep ="")
fullair3$FullName=paste(fullair3$Name, fullair3$NamePart1)
fullair3$NamePart1=NULL


#Make destination specific columns like long and lat
SpitOutNum2=sqldf("select IATA, City, Country, Region, Name, DestinationCount, Longitude, 
Latitude
               from fullair3
               group by IATA,City, Country, Region, Name")
colnames(SpitOutNum2)=c("DestinationAirport","DestCity","DestCountry","DestRegion","DestAirportName","DestCount","DestLong","DestLat")
fullair3=merge(x=fullair3,y=SpitOutNum2,by="DestinationAirport",all.x=TRUE)


#--------------------R Shiny App-------------------#


library(shinydashboard)
library(shiny)
library(leaflet)
library(leaflet.extras)
library(rgdal)
library(sp)
library(raster)

airportchoices=unique(fullair3$FullName)
countrychoices=unique(fullair3$Country)
regionchoices=unique(fullair3$Region)
Italy=subset(fullair3,fullair3$Country=="Italy")

countrychoices <- as.character(countrychoices)
countrychoices <- sort(countrychoices)

# Define UI for application
ui <- fluidPage(
  dashboardPage(
    dashboardHeader(title="Airport Data"),
    dashboardSidebar(
      sidebarMenu(
        menuItem(
          "Maps",
          tabName = "maps",
          icon=icon("globe")
        )
      )
    ),
    dashboardBody(
      tabItems(
        tabItem(
          tabName = "maps",
          tags$style(type="text/css","#all_airports {height:calc(100vh - 80px) !important;}"),

          fluidRow(column(4),
                   column(8,
                          selectInput(inputId = "countryselect",label="Select a country:",choices=countrychoices, selected = "France")
                          )),

          leafletOutput("all_airports")

        )
      )
    )
  )
)

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


  AirportData=reactive({
    filteredData=subset(fullair3,Country == input$countryselect)
    return(filteredData)
  })


  output$all_airports=renderLeaflet({

    data=AirportData()

    pal=colorNumeric("Reds",data$DestinationCount)


    leaflet(data=data) %>% 
      addTiles(group="OpenStreetMap")  %>%


      addCircles(radius = ~data$DestinationCount*250, 
                 weight = 1, 
                 color = "black", 
                 fillColor = ~pal(data$DestinationCount),
                 fillOpacity = 0.7,
                 popup = paste0("Airport Name: ", data$Name, "<br>",
                                "City: ", data$City, "<br>",
                                "Destination Count: ",data$DestinationCount,"<br>"
                 ),
                 label = ~as.character(data$IATA),
                 group = "Points") #%>%



    #addMarkers(lng = ~Longitude,lat = ~Latitude, 
    #           popup=~as.character(DestinationCount), 
    #          label=~as.character(DestinationCount), 
    #          group = "Markers")
  })

}

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