明亮的sliderInput-无法在ggplot2中正确设置并更新它

Question

这是我第一次构建应用程序，我想知道代码中缺少的函数或参数是什么。我想显示一个普通的条形图，该条形图可以动态过滤我希望看到的“公司”，绩效变量（例如“利润”）和日期范围。

我相信我的错误是由于shiny调用中的不精确性造成的，因为我想要的非常简单。您可以通过运行以下代码来获得它（但shiny提供的交互作用是不可能的）：

library(ggplot2)

sample_data = data.frame(Company_Name=c("Company 1","Company 2","Company 3",
                                        "Company 1","Company 2","Company 3",
                                        "Company 1","Company 2","Company 3"),
                         Profits_MM = c(20,100,80,
                                        45,120,70,
                                        50,110,90),
                         Sales_MM = c(200,800,520,
                                        300,1000,630,
                                        410,1150,770),
                         Year=c(2016,2016,2016,
                                2017,2017,2017,
                                2018,2018,2018))

    ggplot(data = sample_data, aes(x=Year, y = Profits_MM, 
    fill=as.factor(Company_Name))) + geom_col(position="dodge")

但是我只提到它，因此可能会对我想要的输出有所了解。我设置的代码实际上是以下代码：

rm(list=ls()); gc()

library(shiny)
library(ggplot2)
library(dplyr)


sample_data = data.frame(Company_Name=c("Company 1","Company 2","Company 3",
                                        "Company 1","Company 2","Company 3",
                                        "Company 1","Company 2","Company 3"),
                         Profits_MM = c(20,100,80,
                                        45,120,70,
                                        50,110,90),
                         Sales_MM = c(200,800,520,
                                        300,1000,630,
                                        410,1150,770),
                         Year=c(2016,2016,2016,
                                2017,2017,2017,
                                2018,2018,2018))


# UI
ui <- fluidPage(

  sidebarLayout(

    # Input(s)
    sidebarPanel(

      checkboxGroupInput(inputId = "sel_com",
                         label = "Company Selection:",
                         choices = c("Company 1","Company 2","Company 3"),
                         selected = "Company 1"),


      selectInput(inputId = "y", 
                  label = "Performance Variable",
                  choices = c("Profits (in Millions)" = "Profits_MM", 
                              "Sales (in Millions)" = "Sales_MM"),
                  selected = "Profits_MM"),


      sliderInput("year","Year Selection:",
                  min=2016,
                  max=2018,
                  value=c(2017,2018),
                  step=1)


    ),

    # Output(s)
    mainPanel(
      plotOutput(outputId = "barplot")
    )
  )
)

# Server
server <- function(input, output, session) {

  companies_sel <- reactive({

    req(input$sel_com)

    filter(sample_data, Company_Name %in% input$sel_com)

  })

  year_sample <- reactive({

    req(input$year)

    if(length(input$year)>1){

      Years = seq(input$year[1],input$year[2])

      filter(companies_sel(), Year %in% Years)

    }  

    if(length(input$year==1)){

      filter(companies_sel(), Year %in% input$year)

    }

  })


  output$barplot <- renderPlot({

    ggplot(data = year_sample(), aes_string(x=input$year, y = input$y, fill=as.factor(input$sel_com))) +

      geom_col(position="dodge")

  })

}

shinyApp(ui = ui, server = server)

我能够获得一些输出，但一次只能获得一家公司，并且不会更改范围大小。也许我不理解observeEvent函数的使用，这可能在其中起作用。那么，如何使inputSlider和其他选项与ggplot2图充分交互？

这里是ouptut错误的一个示例：