R Shiny: Updating proxy table column headers in ObserveEvent - shiny

Question

I would like to update column headers in an R Shiny proxy table. The app should:
Launch with original column header names (e.g. "Do","Re","Mi","Fa","So")
Change those column headers in the proxy table to something else when the user clicks an action button (e.g. "y1","y2","y3","y4","y5")
Shiny has a convenient updateCaption() method that allows for a similar behavior for proxy table captions. I'd like to do something similar with table column headers for proxy tables. Here's my attempt.
library(shiny)
library(DT)
ui <- fluidPage(
fluidRow(
actionButton(
"updatebutton",
label = "Update Table",
style = "margin-right: 5px;"
),
DT::dataTableOutput("myplot")
),
)
server <- function(input, output) {
mycolumnnames <-c("Do","Re","Mi","Fa","So")
myothercolumnnames <- c("y1","y2","y3","y4","y5")
output$myplot <- DT::renderDataTable({
DF <- data.frame(replicate(5, sample(rnorm(5), 10, rep = TRUE)))
datatable(DF, colnames = mycolumnnames,
caption="Original caption")
})
proxy <- DT::dataTableProxy("myplot")
observeEvent(input$updatebutton, {
updateCaption(proxy, caption="Look, I am a NEW caption!")
DF <- data.frame(replicate(5, sample(rnorm(5), 10, rep = TRUE)))
# names(DF) <- myothercolumnnames # This doesn't work
proxy %>% replaceData(DF)
})
}
shinyApp(ui = ui, server = server)

Answer 1

Edit1: Now uses dataTableProxy()
I took away all the things related to color background so I could focus on your problem.
First, I declare some values outside shiny: your data.frame and two vectors for the column names. Then I assign the column names as the first vector.
Inside the app, I retrieve the data as a reactiveVal(), and update its colnames whenever the button is pressed
library(shiny)
library(DT)
mycolumnnames <-c("Do","Re","Mi","Fa","So")
myothercolumnnames <- c("y1","y2","y3","y4","y5")
DF <- data.frame(replicate(5, sample(rnorm(5), 10, rep = TRUE)))
colnames(DF) <- mycolumnnames
ui <- fluidPage(
fluidRow(
actionButton(
"updatebutton",
label = "Update Table",
style = "margin-right: 5px;"
),
DT::dataTableOutput("myplot")
),
)
server <- function(input, output) {
df <- reactiveVal(DF)
output$myplot <- DT::renderDataTable({
datatable(df(), caption="Original caption")
})
observeEvent(input$updatebutton, {
new_data <- data.frame(replicate(5, sample(rnorm(5), 10, rep = TRUE)))
if(!input$updatebutton %% 2 == 0 ){
colnames(new_data) <- myothercolumnnames
} else {
colnames(new_data) <- mycolumnnames
}
df(new_data)
proxy1 <- DT::dataTableProxy("myplot")
updateCaption(proxy1, caption="Look, I am a NEW caption!")
replaceData(proxy1, df())
})
}
shinyApp(ui = ui, server = server)
So whenever you press the button, the colnames are changed between the two vectors.