如何在flash中设置默认的eventReactive变量？

Question

我想仅在用户点击操作按钮时更改颜色参数的值，但在shinyApp的开头我想要默认颜色。

我明白了：

library(shiny)
library(ggplot2)

#data change only once at the begenin
dt <- data.frame(x=runif(100), y=runif(100))


ui <- fluidPage(
  sliderInput("slider1","slider1", value=5, min=1, max=10),
  sliderInput("slider2","slider2", value=0.8, min=0, max=1),
  radioButtons("check1","check1",choices = c("red","blue","green")),
  actionButton("refreshColours","refreshColours"),
  plotOutput("rys")
)



server <- function(input,output){

  col1 <- eventReactive(input$refreshColours,{input$check1}) 

  pp <- reactive({ ggplot(dt, aes(x,y)) + 
      geom_point(size=input$slider1, 
                 alpha=input$slider2, colour=col1()) }) 

  output$rys <- renderPlot({ pp() }) }

shinyApp(ui=ui, server=server)

我只是想看看shinyApp开头的情节，而没有点击动作按钮，所以我需要默认值在＆＃34;颜色＆＃34;在begening变量。

Answer 1

你可以简单地在ggplot中为初始状态设置一个默认值：

pp <- reactive({ ggplot(dt, aes(x,y)) + 
      geom_point(size=input$slider1, 
                 alpha=input$slider2, 
                 colour= if(input$refreshColours == 0) "red" else col1() ) 
    })

Answer 2

得到你想要的东西你可以完全消除第一个col()，我将默认颜色设置为橙色

library(shiny)
library(ggplot2)

#data change only once at the begenin
dt <- data.frame(x=runif(100), y=runif(100))

defaultcolor <- "orange"

ui <- fluidPage(
  sliderInput("slider1","slider1", value = 5, min=1, max=10),
  sliderInput("slider2","slider2", value = 0.8, min=0, max=1),
  radioButtons("check1","check1",choices = c("red","blue","green")),
  actionButton("refreshColours","refreshColours"),
  plotOutput("rys")
)

server <- function(input,output){

  pp <- reactive({ 
    input$refreshColours
    if(input$refreshColours == 0){
      return(ggplot(dt, aes(x,y)) + geom_point(size=input$slider1, alpha=input$slider2, colour= defaultcolor))
    } 
    ggplot(dt, aes(x,y)) + geom_point(size=input$slider1, alpha=input$slider2, colour=input$check1)
    }) 
  output$rys <- renderPlot({ pp() }) }

shinyApp(ui=ui, server=server)

示例2 ：如果您还想使用col()被动，也可以这样做：

library(shiny)
library(ggplot2)

#data change only once at the begenin
dt <- data.frame(x=runif(100), y=runif(100))

defaultcolor <- "orange"

ui <- fluidPage(
  sliderInput("slider1","slider1", value = 5, min=1, max=10),
  sliderInput("slider2","slider2", value = 0.8, min=0, max=1),
  radioButtons("check1","check1",choices = c("red","blue","green")),
  actionButton("refreshColours","refreshColours"),
  plotOutput("rys")
)

server <- function(input,output){

  col1 <- reactive({
    input$refreshColours
    if(input$refreshColours ==0){
      return(defaultcolor)
    }
    input$check1}) 

  pp <- reactive({ 
    ggplot(dt, aes(x,y)) + geom_point(size=input$slider1, alpha=input$slider2, colour=col1())
    }) 
  output$rys <- renderPlot({ pp() }) }

shinyApp(ui=ui, server=server)

Answer 3

除了这里给出的答案是 refreshColors 的数值条件，您可以在调用中将 ignoreNULL = FALSE 设置为 eventReactive，并指定 selected = "blue" （或您喜欢的任何颜色）在对单选按钮的调用中。

#this is basically the code from the question with the above changes added
library(shiny)
library(ggplot2)

#data change only once at the begenin
dt <- data.frame(x=runif(100), y=runif(100))

ui <- fluidPage(
    sliderInput("point_size","Point Size", value=5, min=1, max=10),
    sliderInput("point_alpha","Point Alpha", value=0.8, min=0, max=1),
    #here is where you select the default value with selected
    radioButtons("point_color","Point Color",choices = c("red","blue","green"),selected = "blue"),
    actionButton("refreshColours","Refresh Colors"),
    plotOutput("plot_out")
)

server <- function(input,output){
#set igoreNULL = FALSE here 
    col1 <- eventReactive( input$refreshColours,{input$point_color},ignoreNULL  = FALSE) 
    
    pp <- reactive({ ggplot(dt, aes(x,y)) + 
            geom_point(size=input$point_size, 
                                 alpha=input$point_alpha, colour=col1()) }) 
    
    output$plot_out <- renderPlot({ pp() }) }

shinyApp(ui=ui, server=server)

您还可以在对 radioButtons 的调用中使用 selected = character(0) 以便不选择任何单选按钮来启动，并使用一个函数（下面的color_with_default）返回您选择的默认颜色，如果radioButtons 中的值为 null，因为它是在没有选择时。该默认颜色用于应用启动时呈现的初始绘图中，因为 ignoreNULL 在调用 eventReactive 时为假，就像在前面的示例中一样。

library(shiny)
library(ggplot2)

#data change only once at the begenin
dt <- data.frame(x=runif(100), y=runif(100))


ui <- fluidPage(
    sliderInput("point_size","Point Size", value=5, min=1, max=10),
    sliderInput("point_alpha","Point Alpha", value=0.8, min=0, max=1),
    #use selected = character(0) to start with nothing selected
    radioButtons("point_color","Point Color",choices = c("red","blue","green"),selected = character(0)),
    actionButton("refreshColours","Refresh Colors"),
    plotOutput("plot_out")
)



server <- function(input,output){
    #here is the function that returns a default grey color if no button is selected    
    color_with_default <- function( color_in  ){
        if(is.null(color_in)){
            color_in <- "grey"
        } 
        return(color_in)
    }
    
    col1 <- eventReactive(eventExpr =  input$refreshColours, valueExpr = {input$point_color},ignoreNULL = FALSE) 
    
    pp <- reactive({
        ggplot(dt, aes(x,y)) + 
            geom_point(size=input$point_size, 
                                 #the call to the color_with_default function is here
                                 alpha=input$point_alpha, colour= color_with_default(col1()))
    }) 
    
    output$plot_out <- renderPlot({ pp() }) }


shinyApp(ui=ui, server=server)