关于r：更改闪亮的导入数据集的列类型


Change column type of imported data set in shiny

我想更改导入日期的所选列类型。该操作应在闪亮的应用程序中完成。数据在csv文件中。在此数据集中，应更改的列称为" date "，但是，理想情况下，应该可以输入应更改类型的列的名称。

我编写的代码：

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ui <- fluidPage(
  titlePanel("Test"),
  mainPanel(
    fluidRow(
      column(5,
             fileInput('file1',"Input a csv file:"),
             accept=c('text/csv',
                      'text/comma-separated-values,text/plain',
                      '.csv'),
             checkboxInput('header', 'Header', TRUE)),
      column(3,
             radioButtons('sep', 'Separator',
                          c(Comma=',',
                            Semicolon=';',
                            Tab='\\t'),
                          ',')
      ),
      column(3,
             radioButtons('quote', 'Quote',
                          c(None='',
                            'Double Quote'='"',
                            'Single Quote'="'"),
                          '"')
      )
    ),
    tableOutput("first.two"),
    fluidRow(
      column(4,
             textInput("time.var", h3("Input time variable:"),
                       value =""))
    ),
    p(strong("Variables to choose from:"), textOutput("possible.variables")),
    p(strong("Classes of variables"), textOutput("variable.classes"))
  )
)

server <- function(input, output){
  dset.in <- reactive({
    infile <- input$file1
    if(is.null(infile)){
      return(NULL)
    }

    df <- read.csv(infile$datapath, header = input$header,
                   sep = input$sep,quote = input$quote)

    return(df)}
  )

  # Change column type to date
  # When three lines below are commented out, the code works
  dset.in()$date.input <- observeEvent({
    dset.in()[,input$time.var] <- lubridate::date_decimal(dset.in()[,input$time.var])
  })

  output$first.two <- renderTable({head(dset.in(), 2)})

  output$possible.variables <- renderText(
    names(dset.in())
  )
  output$variable.classes <- renderText(
    sapply(dset.in(), class)
  )
}

shinyApp(ui = ui, server = server)

它会产生以下错误：

Warning in if (!is.na(attribValue)) { :
the condition has length > 1 and only the first element will be used

Warning in charToRaw(enc2utf8(text)) :
argument should be a character vector of length 1
all but the first element will be ignored

Warning in body(fun) : argument is not a function

Warning: Error in eval: argument"expr" is missing, with no default
Stack trace (innermost first):
44: eval
43: makeFunction
42: exprToFunction
41: observeEvent
40: server [#16]
4:
3: do.call
2: print.shiny.appobj
1:

Error in eval(call("function", args, body), env) :
argument"expr" is missing, with no default

尝试使用此：

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  modified_dset <- eventReactive(input$time.var, {
    dset.in()[, input$time.var] <- lubridate::date_decimal(dset.in()[,input$time.var])
  })

并在其他任何地方使用此modified_dset。