Plotly scatter plot in Shiny in R; plot is not updating nor is it fully interactive

Question

I am trying to create an interactive scatter plot within Shiny using the plotly library, where I can plot grouped data and move my cursor over each data point. I am new to plotly but have used Shiny extensively.

Here is a mock example that I have came up with:-

library(shiny)
library(shinyWidgets)
library(plotly)
library(tidyverse)


ui<-fluidPage(
  titlePanel("Iris"),
  tabsetPanel(
    tabPanel("Iris scatter",
             sidebarPanel(width=5,
                          h5("Select the axis variables"),
                          selectInput("eda_scatter_x", "Select x-axis",
                                      c("Sepal Length"="Sepal.Length",
                                        "Sepal Width" ="Sepal.Width",
                                        "Petal Length"= "Petal.Length",
                                        "Petal Width"= "Petal.Width")),
                          selectInput("eda_scatter_y", "Select y-axis",
                                      c("Sepal Length"="Sepal.Length",
                                        "Sepal Width" ="Sepal.Width",
                                        "Petal Length"= "Petal.Length",
                                        "Petal Width"= "Petal.Width")),
                          actionButton(inputId = "eda_run", "Run analysis")),
             mainPanel(
               plotlyOutput("eda_scatter_graph")
             )))
  )


server <- function(input,output,session){
  
  observeEvent(input$eda_run,{
    output$eda_scatter_graph<- renderPlotly({
      iris%>%
        group_by(Species)%>%
        summarise_at(vars(Sepal.Length:Petal.Width),mean)%>%
        plot_ly(x=input$eda_scatter_x, y=input$eda_scatter_y, size=I(c(100,50)))%>%
        add_markers()
        
    })
  })
}


shinyApp(ui,server)

Which gives this output:-

Desired output

What I want to be able to do is plot the grouped data points, so when my cursor moves over the data points, the markers are able to tell me the x-axis and y-axis coordinates plus the grouped variable name (in this case, the Species). Lastly, I want to be able to update the x-axis and y-axis using the selectInput boxes, but when you run the app, it does not update.

Can anyone show me what I am doing wrong and kindly suggest edits?

Thanks :)

Answer 1

Dont use observe event but rather reactive values , and let plotly handle the rest internally

library(shiny)
library(plotly)



ui<-fluidPage(
  titlePanel("Iris"),
  tabsetPanel(
    tabPanel("Iris scatter",
             sidebarPanel(width=10,
                          h5("Select the axis variables"),
                          selectInput('xcol','X Variable', names(iris)),
                          selectInput('ycol','Y Variable', names(iris)),
                          selectInput('color','Group Color', names(iris)),
                  
             mainPanel(
               plotlyOutput("eda_scatter_graph")
             )
             )
            )
    )
  )


server <- function(input,output,session){
  
  x <- reactive({
    iris[,input$xcol]
  })
  
  y <- reactive({
    iris[,input$ycol]
  })
  
  color <- reactive({
    iris[,input$color]
  })

    output$eda_scatter_graph<- renderPlotly(
    plot1<- plot_ly( x=x(), y=y(), type = 'scatter',
                     mode = 'markers', color = color())
      
    )
  
}


shinyApp(ui,server)