Is there a way to preselect points in ggiraph (R shiny)? - r

Question

I would like to preselect some points in a ggiraph::renderggiraph() output.
I can make the following shiny app which allows me to select points and then use those selected points elsewhere like so:
dat <- data.table(x = 1:6, y = 1:6 %% 3, id = 1:6, status = rep(c('on','off'),3))
ui <- fluidPage( ggiraphOutput("plot"),
verbatimTextOutput("choices"))
server <- function(input, output, session){
output$plot <- renderggiraph({
p <- ggplot(dat ) +
geom_point_interactive(aes(x = x, y = y, data_id = id), size = 5) +
scale_color_manual(limits = c('on','off'),values = c('red','black'))
ggiraph(code = print(p),
hover_css = "fill:red;cursor:pointer;",
selection_type = "multiple",
selected_css = "fill:red;")
})
output$choices <- renderPrint({
input$plot_selected
})
}
shinyApp(ui = ui, server = server)
But sometimes I want to have certain points selected before I initialize the app.
For example, if the points 1, 3, and 5 are already "on" orginally, I would like the user to be able to turn them "off".
So my question is, is it possible to achieve something like this?

Answer 1

Yes, by using session$sendCustomMessage in session$onFlushed:
library(shiny)
library(ggiraph)
library(data.table)
library(magrittr)
dat <- data.table(x = 1:6, y = 1:6 %% 3, id = 1:6, status = rep(c('on','off'),3))
ui <- fluidPage( fluidRow(
column(width = 7,
ggiraphOutput("ggobj") ),
column(width = 5, verbatimTextOutput("choices"))
) )
server <- function(input, output, session){
output$ggobj <- renderggiraph({
p <- ggplot(dat ) +
geom_point_interactive(aes(x = x, y = y, data_id = id), size = 5) +
scale_color_manual(limits = c('on','off'),values = c('red','black'))
ggiraph(code = print(p),
hover_css = "fill:red;cursor:pointer;",
selection_type = "multiple",
selected_css = "fill:red;")
})
session$onFlushed(function(){
session$sendCustomMessage(type = 'ggobj_set', message = 1:3)
})
output$choices <- renderPrint({
input$ggobj_selected
})
}
shinyApp(ui = ui, server = server)