ggplot2不知道如何处理类反应的数据

Question

似乎是反应性封装变量，所以推文里面的变量无法访问......那么如何修复呢？或者不使用被动反应？

csv文件tweets_davin并且只使用两者进行2次上传

ui.r

library(shiny)
shinyUI(fluidPage(

  titlePanel("Text Mining"),
  br(),br(),

  sidebarLayout(
    sidebarPanel(
      h2("Davin", align = "center", style = "color:blue"),
      fileInput('file1', 'Choose CSV File', accept=c('.csv')),
      fileInput('file2', 'Choose CSV File', accept=c('.csv')),
      tags$hr()
    ),

    mainPanel(
      plotOutput("ditribusi")

    ))))

server.r

library(shiny)

shinyServer(function(input, output) {

  library(lubridate)
  library(ggplot2)
  library(dplyr)
  library(readr)

  tweets_1 <- reactive({
    req(input$file1)
    read.csv(input$file1$datapath)
  })

  tweets_2 <- reactive({
    req(input$file2)
    read.csv(input$file1$datapath)
  })  

    tweets <- reactive (
    as(bind_rows(tweets_1 %>% 
                          mutate(person = "satu"),
                        tweets_2 %>% 
                          mutate(person = "dua")) %>% 
    mutate(timestamp = ymd_hms(timestamp))))


    output$ditribusi <- renderPlot(
      ggplot(tweets, aes(x = timestamp, fill = person)) +
        geom_histogram(alpha = 0.5, position = "identity", bins = 20)
  )


})

RStudio中的

错误

警告：错误：ggplot2不知道如何处理类被动的数据

堆栈跟踪（最里面的第一个）：

105: fortify.default
104: fortify
103: structure
102: ggplot.data.frame
101: ggplot.default
100: ggplot
 99: renderPlot
 89: <reactive:plotObj>
 78: plotObj
 77: origRenderFunc
 76: output$ditribusi
  1: runApp

Answer 1

reactive返回反应式表达式，而不是值。基本上它意味着可以在反应上下文（内部函数，如reactive，render*等）中访问它的当前值并调用它。我认为应该使用以下代码解决这个特殊问题：

shinyServer(function(input, output) {

  library(lubridate)
  library(ggplot2)
  library(dplyr)
  library(readr)

  tweets_1 <- reactive({
    req(input$file1)
    read.csv(input$file1$datapath)
  })

  tweets_2 <- reactive({
    req(input$file2)
    read.csv(input$file1$datapath)
  })

  tweets <- reactive(
    bind_rows(tweets_1() %>% 
                mutate(person = "satu"),
              tweets_2() %>% 
                mutate(person = "dua")) %>% 
      mutate(timestamp = ymd_hms(timestamp))
    )

  output$ditribusi <- renderPlot(
    ggplot(tweets(), aes(x = timestamp, fill = person)) +
      geom_histogram(alpha = 0.5, position = "identity", bins = 20)
  )
})

有关使用反应式表达式的更多信息，您可以转到https://shiny.rstudio.com/tutorial/lesson6/