为fileInput（shapefile）插入反应式

1. path向function.cl添加一个新参数，删除df不使用的参数，因为该参数直接在函数中分配
2. 在服务器中使用`eventReactive'：

  Modelcl <- eventReactive(input$shp,{
    req(input$shp)
    mydir <- tempdir()
    on.exit(unlink(mydir))
    print(paste("names:",input$shp$name))
    file.copy(input$shp$datapath,file.path(mydir, input$shp$name) )
    function.cl(input$Slider,mydir)
    
  })

困难之处在于readOGR需要一个路径但fileInput返回文件。

解决方法是创建一个临时目录以获取路径（在服务器上），将fileInput文件复制到该目录中，并将该临时目录的路径提供给readOGR进一步处理。

这适用于您提供的示例文件：

library(shiny)
library(ggplot2)
library(shinythemes)
library(rdist)
library(geosphere)
library(rgdal)

function.cl<-function(k,path,filename){
  print(dir(path))
  shape<-readOGR(dsn=path,layer=filename) 
  df<-shape@data
  
  #clusters
  coordinates<-df[c("Latitude","Longitude")]
  d<-as.dist(distm(coordinates[,2:1]))
  fit.average<-hclust(d,method="average") 
  clusters<-cutree(fit.average, k) 
  nclusters<-matrix(table(clusters))  
  df$cluster <- clusters 
  
  #all cluster data df1 and specific cluster df_spec_clust
  df1<-df[c("Latitude","Longitude")]
  df1$cluster<-as.factor(clusters)
  
  #Colors
  my_colors <- rainbow(length(df1$cluster))
  names(my_colors) <- df1$cluster
  
  #Scatter Plot for all clusters
  g <- ggplot(data = df1,  aes(x=Longitude, y=Latitude, color=cluster)) + 
    geom_point(aes(x=Longitude, y=Latitude), size = 4) +
    scale_color_manual("Legend", values = my_colors)
  plotGD <- g
  
  
  return(list(
    "Plot" = plotGD
  ))
}

ui <- bootstrapPage(
  navbarPage(theme = shinytheme("flatly"), collapsible = TRUE,
             "Cl", 
             tabPanel("Solution",
                      fileInput("shp", h3("Shapefile Import"), multiple = TRUE, accept = c('.shp', '.dbf','.sbn', '.sbx', '.shx', '.prj')),
                      sidebarLayout(
                        sidebarPanel(
                          
                          sliderInput("Slider", h5(""),
                                      min = 2, max = 4, value = 3),
                        ),
                        mainPanel(
                          tabsetPanel(      
                            tabPanel("Solution", plotOutput("ScatterPlot"))))
                        
                      ))))

server <- function(input, output, session) {
  
  # Modelcl<-reactive({
  #   function.cl(df,input$Slider,input$Filter1)
  # })
  Modelcl <- eventReactive(c(input$shp, input$Slider),{
    req(input$shp)
    tmpdir <- tempdir()
    on.exit(unlink(tmpdir))
    filename <- substr(input$shp$name[1],1,nchar(input$shp$name[1])-4)
    file.copy(input$shp$datapath,file.path(tmpdir,input$shp$name) )
    function.cl(input$Slider,tmpdir,filename)
    
  })
  
  output$ScatterPlot <- renderPlot({
    Modelcl()[[1]]
  })
  
  observeEvent(input$Slider, {
    abc <- req(Modelcl()$Data)
    updateSelectInput(session,'Filter1',
                      choices=sort(unique(abc$cluster)))
  }) 
  
}

shinyApp(ui = ui, server = server)