as.data.frame.default中的错误：无法将类“c（”reactiveExpr“，”reactive“）”强制转换为Shiny中的data.frame

Question

我遇到了从Shiny中的响应中创建数据帧的问题。该应用程序允许用户上传一些数据，因此该数据集是被动的。然后它将允许用户选择将被传递到回归的输入和输出变量并且生成一个图。 我不断收到一个错误，指出：

Error in as.data.frame.default: cannot coerce class "c("reactiveExpr", "reactive")" to a data.frame 

我相信，它从被认为是用户上传的数据的数据帧我d.f变量的到来。在淘宝上网之后，我一直无法找到解决方法。 任何帮助，将不胜感激。到目前为止的代码如下。

library(shiny) 
library(triangle) 
library(readxl) 
library(leaps) 
library(coefplot) 
library(relaimpo) 
library(data.table) 
library(XLConnect) 
library(xlsx) 

ui <- fluidPage(

    titlePanel("Hi"), 
    sidebarLayout(position = "left", 
       sidebarPanel(
        conditionalPanel(condition = "input.tabs1==1", 
            tags$style(type='text/css', ".well { max-width: 20em; }"), 
            # Tags: 
            tags$head(
            tags$style(type="text/css", "select[multiple] { width: 100%; height:10em}"), 
            tags$style(type="text/css", "select { width: 100%}"), 
            tags$style(type="text/css", "input { width: 19em; max-width:100%}") 
            ), 

            # Select filetype: 
            selectInput("readFunction", "Function to read data:", c(
            # Base R: 
            "read.table", 
            "read.csv", 
            "read.csv2", 
            "read.delim", 
            "read.delim2", 
            "readWorksheet", 
            "read_excel", 
            "read.xlsx" 

            )), 

            # Argument selecter: 
            htmlOutput("ArgSelect"), 

            # Argument field: 
            htmlOutput("ArgText"), 

            # Upload data: 
            fileInput("file", "Upload data-file:"), 

            # Variable selection: 
            htmlOutput("varselect"), 

            br(), 

            uiOutput("invar"), 
            br(), 
            uiOutput("outvar"), 

            textInput("name","Dataset name:","Data")), 
        conditionalPanel(condition = "input.tabs1==2", 
            #fileInput('file', 'Choose file to upload.'), 
            #selectizeInput('invar',"Select Invar", choices = varnames, multiple = TRUE), 
            #selectizeInput('outvar',"Select Outvar", choices = predictors, multiple = FALSE), 
            radioButtons('LM',"Select Regression",choices = list("LM" = 1, "LM2" = 2),selected = 1) 




       )), 
       mainPanel(
        tabsetPanel(id="tabs1", 
           tabPanel("Data File",value = 1,tableOutput("table")), 
           tabPanel("Plot",value=2,tableOutput("Data"),plotOutput("Plot"))  
       ) 
       ) 

)) 



server<-function(input, output) { 
    options(shiny.maxRequestSize=30*1024^2) 

    ### Argument names: 
    ArgNames <- reactive({ 
    Names <- names(formals(input$readFunction)[-1]) 
    Names <- Names[Names!="..."] 
    return(Names) 
    }) 

    # Argument selector: 
    output$ArgSelect <- renderUI({ 
    if (length(ArgNames())==0) return(NULL) 

    selectInput("arg","Argument:",ArgNames()) 
    }) 

    ## Arg text field: 
    output$ArgText <- renderUI({ 
    fun__arg <- paste0(input$readFunction,"__",input$arg) 

    if (is.null(input$arg)) return(NULL) 

    Defaults <- formals(input$readFunction) 

    if (is.null(input[[fun__arg]])) 
    { 
     textInput(fun__arg, label = "Enter value:", value = deparse(Defaults[[input$arg]])) 
    } else { 
     textInput(fun__arg, label = "Enter value:", value = input[[fun__arg]]) 
    } 
    }) 


    ### Data import: 
    Dataset <- reactive({ 
    if (is.null(input$file)) { 
     # User has not uploaded a file yet 
     return(data.frame()) 
    } 

    args <- grep(paste0("^",input$readFunction,"__"), names(input), value = TRUE) 

    argList <- list() 
    for (i in seq_along(args)) 
    { 
     argList[[i]] <- eval(parse(text=input[[args[i]]])) 
    } 
    names(argList) <- gsub(paste0("^",input$readFunction,"__"),"",args) 

    argList <- argList[names(argList) %in% ArgNames()] 

    Dataset <- as.data.frame(do.call(input$readFunction,c(list(input$file$datapath),argList))) 
    return(Dataset) 
    }) 

    # Select variables: 
    output$varselect <- renderUI({ 

    if (identical(Dataset(), '') || identical(Dataset(),data.frame())) return(NULL) 

    # Variable selection:  
    selectInput("vars", "Variables to use:", 
       names(Dataset()), names(Dataset()), multiple =TRUE)    
    }) 

    # Show table: 
    output$table <- renderTable({ 

    if (is.null(input$vars) || length(input$vars)==0) return(NULL) 

    return(Dataset()[,input$vars,drop=FALSE]) 
    }) 

    ################################################################################# 

    varnames<-reactive({ 
    names(input$readFunction) 
    }) 

    output$invar<-renderUI({ 
    selectizeInput('invar',"Select Invar", choices = names(Dataset()), multiple = TRUE) 
    }) 

    output$outvar<-renderUI({ 
    selectizeInput('outvar',"Select Outvar", choices = names(Dataset()), multiple = TRUE) 

    }) 

    d.f<-Dataset 

    output$Plot <- renderPlot({  

    SelectedVars <- input$invar 
    vartopredict <- input$outvar 

     fmla <- reformulate(SelectedVars, response = vartopredict) 
     pred.model=lm(fmla,d.f) 
     plot(pred.model) 
     abline(a=0,b=1,col="red") 


    }) 
} 

    shinyApp(ui = ui, server = server) 

Answer 1

正如Chi Pak所提到的，被动表达式必须在末尾包含（）。将d.f更改为d.f（）可以解决问题。