Question

我使用R和shiny来查询SQL数据库。用户可以搜索并添加到反应数据帧，其输出在ggplot中绘制。但是，我需要将反应数据帧的列更改为绘图的因子。我可以使用ggplot（aes(factor(...),）直接执行此操作。但是，如果我添加使用反应输入更改绘制变量的选项，我必须使用aes_string。如果我使用aes_string，它不喜欢aes(factor(...),。这是一个有效的例子：

服务器：

# Create example data

set.seed(10)
MeasurementA <- rnorm(1000, 5, 2)
MeasurementB <- rnorm(1000, 5, 2)

Wafer <- rep(c(1:100), each=10)
ID <- rep(c(101:200), each=10)
Batch <- rep(c(1:10), each=100)

dd <- data.frame(Batch, Wafer, ID, MeasurementA, MeasurementB)

# Create local connection (in reality this will be a connection to a host site)

con <- dbConnect(RSQLite::SQLite(), ":memory:")
dbWriteTable(con, "dd", dd)
query <-  function(...) dbGetQuery(con, ...)

# Create empty data frames to populate

wq = data.frame()
sq = data.frame()

shinyServer(function(input, output){

  # create data frame to store reactive data set from query
  values <- reactiveValues()
  values$df <- data.frame()

  # Action button for first query
  d <- eventReactive(input$do, { input$wafer })

  # First stage of reactive query
  a <- reactive({ paste("Select ID from dd where Wafer=",d(), sep="") })

  wq <- reactive({  query( a() ) })

  # Output to confirm query is correct
  output$que <- renderPrint({ a() }) 
  output$pos <- renderPrint( wq()[1,1] )  

  # Action button to add results from query to a data frame
  e <- eventReactive(input$do2, { wq()[1,1] })

  b <- reactive({ paste("select Wafer, Batch, MeasurementA, MeasurementB from dd where ID=",e()," Order by  ID asc ;", sep="") })

  # observe e() so that data is not added until user presses action button  
  observe({
    if (!is.null(e())) {
      sq <- reactive({  query( b() ) })

      # add query to reactive data frame
      values$df <- rbind(isolate(values$df), sq())
    }
  })


# output of results  

  # Without mesurement choice (works)
  output$boxV <- renderPlot({
  ggplot(values$df, aes(factor(Wafer), MeasurementA, fill=factor(Batch))) + geom_boxplot() 
  })
  # With measurement choice (doesnt work)
  #output$boxV <- renderPlot({
    #ggplot(values$df, aes_string(factor('Wafer'), input$char, fill=factor('Batch'))) + geom_boxplot() 
  #})

  })

UI：

library(markdown)

shinyUI(fluidPage(
  titlePanel("Generic grapher"),
  sidebarLayout(
    sidebarPanel(

      numericInput("wafer", label = h3("Input wafer ID:"), value = NULL),

      actionButton("do", "Search wafer"),
      actionButton("do2", "Add to data frame"),
      selectInput("char", label="Boxplot choice:",
                  choices = list("A"="MeasurementA", "B"="MeasurementB"),                            
                  selected="Von.fwd")

      ),

      mainPanel(
        verbatimTextOutput("que"), 
        verbatimTextOutput("pos"),
        plotOutput("boxV")
      )
    )
  )
)

我添加了工作和非工作的输出图代码（非工作已注释掉）。

现在，我读过这个（Formatting reactive data.frames in Shiny）和这个（R shiny modify reactive data frame），但我很困惑。因为我使用reactiveValues来存储数据，所以我使用代码值$ df来访问数据...但是如果我想将列转换为上述目的的因素呢？这似乎不起作用：

new <- reactive(as.factor(values$df$Wafer))

也许我正在咆哮错误的树？

Answer 1

好的，我通过更改查询本身的数据类型来解决问题：

b <- reactive({ paste("select cast(Wafer as varchar) as Wafer, cast(Batch as varchar) as Batch, MeasurementA, MeasurementB from dd where ID=",e()," Order by  ID asc ;", sep="") })

那样我以后就不用乱了。它适用于我，但如果有人读这篇文章想告诉我这是一个坏主意，请做。我是SQL和R的新手所以请纠正我，这样我就可以学习。感谢

使用reactiveValues和ggplot处理闪亮

1 个答案: