R Shiny:在反应式数据框中创建新列 [英] R Shiny: Creating New Columns Within a Reactive Data Frame
问题描述
假设我有一个名为 summarized
的数据框,其中包括 TY_COMP
和 LY_COMP
列(等等).我可以在 R 中编写一个函数,对 TY_COMP
和 LY_COMP
执行计算,并在数据框中创建一个名为 cac
的新列,如下所示:
Say I have a data frame called summarized
which includes the columns TY_COMP
and LY_COMP
(among others). I could write a function in R that performs a calculation on TY_COMP
and LY_COMP
and creates a new column called cac
in the data frame like this:
summarized$cac <- summarized$TY_COMP/summarized$LY_COMP-1
cac
现在是汇总数据框中的一个新列.
cac
is now a new column in the summarized data frame.
现在说 summarized()
是一个具有相同列的反应式数据框.
Now say that summarized()
is a reactive data frame with the same columns.
如何实现在非反应数据框中完成的效果,即在当前帧中创建一个新列?或者我怎么会得到同样的效果?
How could I achieve the effect done in the non-reactive data frame, i.e. create a new column within the current frame? Or how would I get the same effect?
我试过了:
summarized$cac <- reactive({summarized()$TY_COMP/summarized()$LY_COMP-1})
推荐答案
我想你想修改一个 reactive
例如当一个 actionButton
被点击时.为此,我将使用 reactiveValues
.您可以在诸如 observe
或 observeEvent
之类的观察者内部修改 reactiveValue
.
I reckon you want to modify a reactive
when for example an actionButton
is clicked. For this purpose I would use reactiveValues
. You can modify reactiveValue
inside of observers such as observe
or observeEvent
.
看看这个简单的例子:
summarized <- data.frame(id = 1:20, group = letters[1:4], TY_COMP = runif(20), LY_COMP = runif(20))
library(shiny)
ui <- fluidPage(
verbatimTextOutput("text"),
actionButton("btn", "Add the 'cac' column to summarized")
)
server <- function(input, output){
rv <- reactiveValues(summarized = summarized)
output$text <- renderPrint(rv$summarized)
observeEvent(input$btn, {
rv$summarized$cac <- summarized$TY_COMP / summarized$LY_COMP - 1
})
summarized_mod <- reactive({
summarized()$TY_COMP / summarized()$LY_COMP-1
})
}
shinyApp(ui, server)
另一种选择是创建另一个具有附加列的 reactive
.这可以使用,但根据您的用例,我推荐第一种解决方案.
Another option would be to create another reactive
that has an additional column. This is possible to use, but depending on your use case, I recommend the first solution.
示例:
summarized <- data.frame(id = 1:20, group = letters[1:4], TY_COMP = runif(20), LY_COMP = runif(20))
library(shiny)
ui <- fluidPage(
verbatimTextOutput("text1"),
verbatimTextOutput("text2")
)
server <- function(input, output){
output$text1 <- renderPrint(summarized_orig())
output$text2 <- renderPrint(summarized_mod())
summarized_orig <- reactive( {
summarized
})
summarized_mod <- reactive({
df <- summarized_orig()
df$cac <- summarized_orig()$TY_COMP / summarized_orig()$LY_COMP - 1
df
})
}
shinyApp(ui, server)
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