r - Using Proxy Interface in Plotly/Shiny to dynamically change data

Question

I want to update the data present in a plot (displayed in plotlyOutput in a Shiny app) using Proxy Interface. Here is a minimal App.R code :

library(shiny)
library(plotly)

ui <- fluidPage(
    actionButton("update", "Test"),
    plotlyOutput("graphe")
)

server <- function(input, output, session) {
    output$graphe <- renderPlotly({
        p <- plot_ly(type="scatter",mode="markers")
        p <- layout(p,title="test")
        p <- add_trace(p, x=0,y=0,name="ABC_test",mode="lines+markers")
    })

    observeEvent(input$update, {
        proxy <- plotlyProxy("graphe", session) %>%
            plotlyProxyInvoke("restyle", list(x=0,y=1),0)
    })
}

shinyApp(ui, server)

When I run it, the plot is displayed with a dot at (0,0) (as wanted) but when I click of the button "Test", the dot does not move to (0,1). How can I achieve this ?

Thank you for any answer.

Answer 1

Strangely enough addTracesdoes not work with only one point but works with two points. To make it work you could add the same point twice. So you could try this:

ui <- fluidPage(
  actionButton("update", "Test"),
  plotlyOutput("graphe")
)

server <- function(input, output, session) {
  output$graphe <- renderPlotly({
    p <- plot_ly(type="scatter",mode="markers")
    p <- layout(p,title="test")
    p <- add_trace(p, x=0,y=0,name="ABC_test",mode="lines+markers")
  })

  observeEvent(input$update, {
    plotlyProxy("graphe", session) %>%
    plotlyProxyInvoke("deleteTraces", list(as.integer(1))) %>%
    plotlyProxyInvoke("addTraces", list(x=c(0, 0),y=c(1, 1),
                        type = 'scatter',
                        mode = 'markers'))
  })
}

shinyApp(ui, server)