R闪亮的数值输入步长和最小值交互作用

问题描述

在R Shiny应用程序中考虑以下数字小部件:

Consider the following numeric widget in an R Shiny app:

numericInput("val", "Enter value:", value = 50, min = 0, step = 5)

如果在运行应用程序时单击窗口小部件中的向上/向下箭头，则该值将按预期增加或减少5(0、5、10、15 ...).

If you click on the up/down arrows in the widget when the app is run, the value will increase or decrease by 5 (0, 5, 10, 15,...) as expected.

现在考虑将最小值更改为1:

Now consider changing the min value to 1:

numericInput("val", "Enter value:", value = 50, min = 1, step = 5)

如果现在单击向上/向下箭头，该值仍会增加/减少5，但从1开始，创建顺序1、6、11、16 ...

If you now click on the up/down arrows, the value will still increase/decrease by 5, but start from 1, creating the sequence 1, 6, 11, 16,...

当最小值为1时，是否可以维持5的增减，但从0开始(因此顺序为0、5、10、15 ...)?

Is it possible to maintain increments/decrements of 5 but starting from 0 (so the sequence is 0, 5, 10, 15,...) when the min value is 1?

一个可能需要这样做的示例(例如，在我的情况下)是您希望用户输入一个(严格地)正数，但由于5的倍数很好，很容易，所以递增/递减值为5，四舍五入的数字(而不是1、6、11、16等)

An example where this might be needed (as in my case) is where you wish to have the user enter a (strictly) positive number, but have an increment/decrement value of 5 since multiples of 5 are nice, easy, rounded numbers (as opposed to 1, 6, 11, 16,... etc.)

推荐答案

您可以使用updateNumericInput来防止numericInput中的空值.这是一个示例:

You can use updateNumericInput to prevent null value in your numericInput. Here is an example:

library(shiny)

ui <- fluidPage(
  sidebarPanel(
    numericInput("val", "Enter value:", value=50, min = 0, step = 5)
  )
)

server <- function(input, output, session) {
  observeEvent(input$val, {
    x <- input$val
    if (x == 0 | is.na(x)){
      updateNumericInput(session, "val", value = 1)
    }
  })
}

shinyApp(ui, server)

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