radioButtons() 输入作为在 Shiny 中过滤数据框的条件，似乎不起作用

Question

使用来自ggplot2 的midwest 数据框：

# (in app_ui.r)

poverty_sidebar <- sidebarPanel(
  radioButtons(
    inputId = "state",
    label = "State",
    choices = list("IL" = 1, "IN" = 2, "MI" = 3, "OH" = 4, "WI" = 5),
    selected = 1
  ))

poverty_plot <- mainPanel(
  plotOutput(
    outputId = "poverty_plot"
  )
)

# (in app_server.r)

server <- function(input, output) {
  
  output$poverty_plot <- renderPlot({
    
    filtered <- filter(midwest, state == input$state)
    
    plot <- ggplot(data = filtered) +
      geom_col(x = county, y = poppovertyknown)
    
    return(plot)
  })
  

似乎不起作用，给我一个“找不到对象county”错​​误。是在做filter(midwest, state == input$state) 错误的方法吗？还是错误出在我的单选按钮上？

Answer 1

所以提供的代码很接近，你犯了两个错误

1. choices 不需要映射到数字
2. x = county, y = poppovertyknown 应该在 aes 的 geom_col 所以 aes(x = county, y = poppovertyknown)

因此最终的工作代码将是（注意，我已将分配添加到 ui 以使其在单个文件中工作，并调用 shinyApp(ui, server)），

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


poverty_sidebar <- sidebarPanel(
  radioButtons(
    inputId = "state",
    label = "State",
    choices = list("IL", "IN", "MI", "OH", "WI"), # remove mapping to integers
    selected = "IL"
  ))

poverty_plot <- mainPanel(
  plotOutput(
    outputId = "poverty_plot"
  )
)

ui <- 
  fluidPage(
    poverty_sidebar,
    poverty_plot
  )
  

# (in app_server.r)

server <- function(input, output) {
  
  output$poverty_plot <- renderPlot({
    
    filtered <- filter(midwest, state == input$state)
    print(filtered)
    print(input$state)
    filtered0 <<- filtered
    plot <- 
      filtered %>% 
      ggplot() +
      geom_col(aes(x = county, y = poppovertyknown)) # used aes()
    
    return(plot)
  })
  
}

shinyApp(ui, server)