r - Shiny 没有像我期望的那样显示我的 ggplot

Question

是什么让我的 Shiny 小应用程序无法显示我的 ggplot？当我将 renderPlot() 中的代码替换为使用基本绘图函数的示例时，它会结合在一起。我在 Windows Vista 上使用 RStudio, R v3.0.1，输出到 Chrome 浏览器。

ui.r

library(ggplot2)

cities <- c("Anchorage","Fairbanks","Juenau","Wasilla","Homer")
years <- 2003:2013
Table <- "Capital Assets"
Account <- c("Land", "Art", "Buildings", "Equipment")
dat <- data.frame(City = sort(rep(cities, length(years))), Year = rep(years,length(cities)), Table)
sampleDat <- rbind(data.frame(dat,Acount = Account[1]), data.frame(dat, Acount = Account[2]), data.frame(dat, Acount = Account[3]), data.frame(dat, Acount = Account[4]))
finalDat <- data.frame(sampleDat, Value = runif(length(sampleDat[,1]), 1000,10000) )

shinyUI(pageWithSidebar(

  headerPanel("CAFR Explorer"),

  selectInput("city","City", as.list(levels(finalDat$City)), selected = NULL, multiple = FALSE),

  mainPanel(
    h3(textOutput("caption")),

    plotOutput("CAFRplot")
)))   

server.r

library(shiny)
library(ggplot2)

cities <- c("Anchorage","Fairbanks","Juenau","Wasilla","Homer")
years <- 2003:2013
Table <- "Capital Assets"
Account <- c("Land", "Art", "Buildings", "Equipment")
dat <- data.frame(City = sort(rep(cities, length(years))), Year = rep(years,length(cities)), Table)
sampleDat <- rbind(data.frame(dat,Acount = Account[1]), data.frame(dat, Acount = Account[2]), data.frame(dat, Acount = Account[3]), data.frame(dat, Acount = Account[4]))
finalDat <- data.frame(sampleDat, Value = runif(length(sampleDat[,1]), 1000,10000) )

shinyServer(function(input, output) {

  formulaText <- reactive({
    paste(input$city)
  })

  output$caption <- renderText({
    formulaText()
  })

  output$CAFRplot <- renderPlot({

    ## this one isn't working.
    ggplot(finalDat, aes(x = finalDat[which(finalDat$City == input$city),2], 
                         y = finalDat[which(finalDat$City == input$city),5])) +
    geom_point()

    ## this one is working
    #plot(finalDat[which(finalDat$City == input$city),2], y = finalDat[which(finalDat$City == input$city),5])


  })
})

Answer 1

这里有两个问题。

首先，您不应该在 aes 中设置子集-- 它需要列名。相反，将您提供给 ggplot 的 data.frame 子集化(感谢来自 R 聊天的@Roland)

其次，必须明确print您 Shiny 的应用程序中的 ggplot 对象。

尝试这个:

p <- ggplot(finalDat[finalDat$City == input$city,], aes(x = Year, y = Value))
p <- p + geom_point()
print(p)