如何在闪亮的开始时将投递箱清空

Question

我使用下拉框显示三个选项，

selectInput("select", label = h5("Choose Annotation DB"),
                                          choices = list("h10kcod.db"="h10kcod","h20kcod.db"="h20kcod","hwgcod.db"="hwgcod")),
                                       selected = NULL)

但它始终在已选择的下拉框中具有第一选择，但是我有兴趣将下拉框清空（没有选择任何一个）。我该怎么做。谢谢

Answer 1

你好，看看这个例子：

library("shiny")

ui = fluidPage(
  # method 1 : put an empty element "" in your list
  selectInput("select", label = h5("Choose Annotation DB"),
              choices = list("",     "h10kcod.db"="h10kcod","h20kcod.db"="h20kcod","hwgcod.db"="hwgcod")),
  # method 2 : use selectizeInput and the placeholder option
  selectizeInput("select", label = h5("Choose Annotation DB"),
          choices = list("h10kcod.db"="h10kcod","h20kcod.db"="h20kcod","hwgcod.db"="hwgcod"),
          options = list(placeholder = 'A placeholder',
                         onInitialize = I('function() { this.setValue(""); }')))
)

server = function(input, output) {

}

shinyApp(ui = ui, server = server)