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[英]How to use original and updated version of reactive data.table in Shiny?
[英]Initializing and updating a reactive (data.table) in Shiny?
是否有可能使有光泽的反应性初始化? 我想要一个反应性的data.table。 此data.table的一部分不会更改,因此每次输入更改时都不需要重新初始化它,而仅需要更新列“ original_values”和“ working_values”。
这可能吗? 还是这样的情况 ,即使我在这里计算值并且没有副作用 ,也可以更好地将activeValues()与observe()结合使用 ?
library(shiny)
library(data.table)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
sliderInput("slider1", "Slider 1",min = 0.1, max = 1, value = 0.4, step = 0.05),
sliderInput("slider2", "Slider 2",min = 0.1, max = 1, value = 0.4, step = 0.05),
sliderInput("slider3", "Slider 3",min = 100, max = 20000, value = 5000, step= 200)
),
mainPanel(
tableOutput("tableOut")
)
))
server <- function(input, output, session){
rv_dtWeights <- reactive({
#initalization - can this be put somewhere else?
ret <- data.table(slider_names= c("slider1","slider2", "slider3"),
some_grouping_information=c("A", "A", "B") )
#actual reactive
ret[,original_values :=c(input$slider1,input$slider2,input$slider3)]
ret[,working_values:=sum(original_values), by=some_grouping_information]
})
output$tableOut<- renderTable(rv_dtWeights())
}
shinyApp(ui = ui, server=server)
您可以将其放在reactive
之外,也可以放在server
(或放在server
外部,有关差异的更多信息,请参见此处 )。 下面给出一个示例,其中当用户打开应用程序时, data.table
仅初始化一次。
希望这可以帮助!
library(shiny)
library(data.table)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
sliderInput("slider1", "Slider 1",min = 0.1, max = 1, value = 0.4, step = 0.05),
sliderInput("slider2", "Slider 2",min = 0.1, max = 1, value = 0.4, step = 0.05),
sliderInput("slider3", "Slider 3",min = 100, max = 20000, value = 5000, step= 200)
),
mainPanel(
tableOutput("tableOut")
)
))
server <- function(input, output, session){
#initalization - can this be put somewhere else?
ret <- data.table(slider_names= c("slider1","slider2", "slider3"),
some_grouping_information=c("A", "A", "B") )
rv_dtWeights <- reactive({
#actual reactive
ret[,original_values :=c(input$slider1,input$slider2,input$slider3)]
ret[,working_values:=sum(original_values), by=some_grouping_information]
})
output$tableOut<- renderTable(rv_dtWeights())
}
shinyApp(ui = ui, server=server)
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