闪亮的 R 直方图不随滑块变化

Question

我正在尝试在 dataset 上使用 shiny 创建直方图。我希望能够在其上使用滑块来更改直方图的数量。我的数据集有一列（cocoa 百分比），其值在 [50, 100] 中。在将其设为数字而不是分类后，我会使用直方图查看 50、51 的频率，...或 50-55、56-60 的频率，... 我写了这段代码，但是当我运行它时没有任何反应。我究竟做错了什么？你能帮我让它工作吗？


library(shiny)
library(shinythemes)
library(ggplot2)
library(plotly)
library(leaflet)
library(DT)

ui <- fluidPage(

    titlePanel("Chocolate Bar Ratings"),

        # Sidebar with a slider input for number of bins 
    sidebarLayout(
        sidebarPanel(
            sliderInput("bins",
                        "Number of bins:",
                        min = 1,
                        max = 50,
                        value = 1)
        ),

        # Show a plot of the generated distribution
        mainPanel(
           plotOutput("distPlot")
        )
    )
)

server <- function(input, output) {

    output$distPlot <- renderPlot({
        # generate bins based on input$bins from ui.R
        x    <- faithful[, 2]
        bins <- seq(min(x), max(x), length.out = input$bins + 1)

        # draw the histogram with the specified number of bins
        hist(chocolate$CocoaPerc, xlab="Percentuale di cacao", main="Frequenza della percentuale
di cacao", col = c("chocolate", "chocolate3", "chocolate2", "chocolate4"))

    })
}

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

Answer 1

原因是 input$bins 没有在 output$distPlot 函数中使用，参见 # <--- 注释。另请注意，我刚刚发明了一个随机数据集：

library(shiny)

chocolate <- data.frame(CocoaPerc=runif(100, min=0, max=99))

ui <- fluidPage(

  titlePanel("Chocolate Bar Ratings"),

  # Sidebar with a slider input for number of bins 
  sidebarLayout(
    sidebarPanel(
      sliderInput("bins",
                  "Number of bins:",
                  min = 1,
                  max = 50,
                  value = 1)
    ),

    # Show a plot of the generated distribution
    mainPanel(
      plotOutput("distPlot")
    )
  )
)

server <- function(input, output) {

  output$distPlot <- renderPlot({
    # draw the histogram with the specified number of bins
    hist(chocolate$CocoaPerc, 
         nclass = input$bins, # <---
         xlab="Percentuale di cacao", 
         main="Frequenza della percentuale di cacao", 
         col = c("chocolate", "chocolate3", "chocolate2", "chocolate4"))
  })
}

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

闪亮的 R 直方图不随滑块变化

Shiny R histogram not changing with slider

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