R（闪亮）：创建一个下拉列表，可以动态生成图表

Question

我想知道如何使用下拉菜单传递数据框作为输入参数，然后动态生成图表。我已经能够创建一个正确呈现UI的闪亮应用程序，但它总是生成与2012数据相关联的图表（无论从下拉菜单中选择什么年份）。看起来发生的情况是，我使用的renderPlot函数没有识别input $ year参数，所以我的控制流程只呈现最后一个ggplot（在“else”语句之后）。我的问题是，我如何在ui.R文件中创建来自下拉菜单的输入，以便被server.R文件识别，并允许用户根据他们选择的年份动态呈现图表。这是否涉及使用reactive()函数？任何帮助将不胜感激。

以下是server.R代码：

library(ggplot2)
library(plyr)
library(shiny)

business1986 <- readRDS("data/business1986.rds")
business1991 <- readRDS("data/business1991.rds")
business1999 <- readRDS("data/business1999.rds")
business2005 <- readRDS("data/business2005.rds")
business2012 <- readRDS("data/business2012.rds")

shinyServer(function(input, output){

    output$Plot <- renderPlot({
    if(input$year == "1986") {     
        ggplot(business1986, aes(x=Category, y=Workers)) + geom_bar(stat="identity", aes(fill=Category)) +
            labs(title="Number of Workers in Orange County by Sector, 1986") +
            theme(plot.title = element_text(face="bold", size = 17, vjust = 1.5)) +
            theme(legend.title = element_text(size=13)) +
            scale_y_continuous(labels = comma) + scale_fill_brewer() 
    } else if(input$year == "1991") {
        ggplot(business1991, aes(x=Category, y=Workers)) + geom_bar(stat="identity", aes(fill=Category)) +
            labs(title="Number of Workers in Orange County by Sector, 1991") +
            theme(plot.title = element_text(face="bold", size = 17, vjust = 1.5)) +
            theme(legend.title = element_text(size=13)) +
            scale_y_continuous(labels = comma) + scale_fill_brewer() 
    } else if(input$year == "1999"){
        ggplot(business1999, aes(x=Category, y=Workers)) + geom_bar(stat="identity", aes(fill=Category)) +
            labs(title="Number of Workers in Orange County by Sector, 1999") +
            theme(plot.title = element_text(face="bold", size = 17, vjust = 1.5)) +
            theme(legend.title = element_text(size=13)) +
            scale_y_continuous(labels = comma) + scale_fill_brewer() 
    } else if(input$year == "2005") {
        ggplot(business2005, aes(x=Category, y=Workers)) + geom_bar(stat="identity", aes(fill=Category)) +
            labs(title="Number of Workers in Orange County by Sector, 2005") +
            theme(plot.title = element_text(face="bold", size = 17, vjust = 1.5)) +
            theme(legend.title = element_text(size=13)) +
            scale_y_continuous(labels = comma) + scale_fill_brewer() 
    } else {
        ggplot(business2012, aes(x=Category, y=Workers)) + geom_bar(stat="identity", aes(fill=Category)) +
            labs(title="Number of Workers in Orange County by Sector, 2012") +
            theme(plot.title = element_text(face="bold", size = 17, vjust = 1.5)) +
            theme(legend.title = element_text(size=13)) +
            scale_y_continuous(labels = comma) + scale_fill_brewer() 
    }
            })

    })

这里是ui.R代码：

shinyUI(fluidPage(
    titlePanel("Economic Change in Orange County, CA"),
    sidebarLayout(
        sidebarPanel(h3("Choose a Year"), position="left",
        helpText("Observe econommic change in Orange County between 1986 and 2010
                 by adjusting the controls below."),
        selectInput("year", label = h5("Select Year"), 
                    choices = list("1986" = 1, "1991" = 2,
                                   "1999" = 3, "2005" = 4,
                                   "2012" = 5), selected = 1)),
        mainPanel(h3("Business Sector Composition"), 
                  plotOutput("Plot"), 
                  position="right")
    )
    )
)

- benpiggot

---

我不能确定因为你没有提供测试你的代码所需的数据，但看起来你检查的是名字而不是 input$year 的值在你的 if..else 代码块。尝试使用 if(input$year == 1)等语句替代 if(input$year == "1986")，看看是否起作用。 - nrussell

太好了，我会尝试的。 - benpiggot

谢谢，那个方法可行！虽然解决方案会更加复杂！ - benpiggot

@user3619356 如果你将c（“1986”，“1991”，“1999”，“2005”，“2012”）传递给choices参数，而不是命名列表，你的代码就可以工作了（顺便说一句，你也可以使用命名向量，调用c而不是list，但传入相同的参数...我认为Shiny会以相同的方式处理它们）。但是，在我看来，命名向量更好。 - shadowtalker

Answer 1

我使用了这段代码，它在我描述的相同情况下可以正常工作。Reactive()是我使用的方法。

ui <- fluidPage(
  sidebarLayout(

  sidebarPanel(
  selectInput(inputId = "diamonds", 
              label = "choose a category in Diamonds", 
              choices = c("Length", "Breath", "Height"," Please Select a Type "),


  ))

)

server <- function(input, output){

  datasetInput <- reactive({ 
    switch(input$dataset, 
           "Length" = diamonds$x, 
           "Breath" = diamonds$y, 
           "Height" = diamonds$z,
           " Please Select a Type " = NULL) 
  }) 

- Sovik Gupta