r语言 - 使用文本输入来计算另一个文本输入的值

Question

我想给输入百分比或值的选项。当用户输入其中一个时，我希望另一个自动填充。

对于代码:

textInput(DownDollars, "Downpayment (Dollars)", value = "", width = NULL, placeholder = NULL),
textInput(DownPercent, "Downpayment (Percent)", value = "", width = NULL, placeholder = NULL)

是否有办法使用这些输入的输出来替代value =选项?

更新:下面的代码不能使用另一个输入作为参考值:

ui <- fluidPage(
numericInput("HomePrice", "Home Price", value = ""),

numericInput("DownPaymentDollars", "Down Payment (Dollars)", value = "", width = NULL),

numericInput("DownPaymentPercent", "Down Payment (Percent)", value = "", width = NULL)
)
server = function(input, output, session){

#referenceValue <- 254

observeEvent(input$DownDollars, {
updateNumericInput(session, "DownPaymentPercent", value = input$DownDollars * 100 / input$HomePrice)
})

observeEvent(input$DownPercent, {
updateNumericInput(session, "DownPaymentDollars", value = input$DownPercent * input$HomePrice / 100)
})

}
shinyApp(ui, server)

Answer 1

首先，使用numericInput获取数值更容易。下面的代码可以满足您的需求:

library(shiny)

ui <- fluidPage(
numericInput("DownDollars", "Downpayment (Dollars)", value = "", width = NULL),

numericInput("DownPercent", "Downpayment (Percent)", value = "", width = NULL)
)
server = function(input, output, session){

referenceValue <- 254

observeEvent(input$DownDollars, {
updateNumericInput(session, "DownPercent", value = input$DownDollars * 100 / referenceValue)
})

observeEvent(input$DownPercent, {
updateNumericInput(session, "DownDollars", value = input$DownPercent * referenceValue / 100)
})

}
shinyApp(ui, server)

我定义了一个referenceValue来计算百分比，您可以根据需要定义这个值，例如从另一个用户输入中获取。

注意用引号定义输入id。

编辑

当使用另一个numericInput获取参考值时，您需要观察这个新的numericInput来更新计算。两个updateNumericInput中的一个必须同时被两个observeEvent触发(参见这篇解释语法的文章):

library(shiny)

ui <- fluidPage(
numericInput("HomePrice", "Home Price", value = ""),
numericInput("DownDollars", "Downpayment (Dollars)", value = "", width = NULL),

numericInput("DownPercent", "Downpayment (Percent)", value = "", width = NULL)
)
server = function(input, output, session){


observeEvent({
input$HomePrice
input$DownDollars
}, {
updateNumericInput(session, "DownPercent", value = input$DownDollars * 100 / input$HomePrice)
})

observeEvent(input$DownPercent, {
updateNumericInput(session, "DownDollars", value = input$DownPercent * input$HomePrice / 100)
})

}
shinyApp(ui, server)