"Circular" reactivity question

shiny
#1

I'm not sure what the best phrase in SWE is to describe such a problem, but I have come across a challenge recently on a few projects.

I am using leaflet to show a choropleth map of multiple locations. I also have a single trendline ggplot with a selectInput filtering the plot to one of said locations. When I click on an area on the map the selectInput is updated. But here's where the "circular" or two-way reactivity part comes in, I also want the map to "flyTo()" a location when I change the selectInput.

Implementing this causes issues of "double" reaction.

I can provide a reprex if needed but I feel this is a common problem outside of this literal example. Thanks in advance

#2

a reprex would make it easier to understand your problem, and to provide you with a solution.

#5

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#3

Here's a reprex of a set up that I thought was analogous to what you describe, but I don't see any substantial problem with it, and I set up it sort of 'naturally'.

library(shiny)
library(plotly)
gdata<- data.frame(
  a=c(1,3,2),
  b=c(2,4,4),
  c=c(3,2,1)
)
ui <- fluidPage(
  selectInput(inputId = "myselect",
              label = "selectinput",
              choices = letters[1:3]),
  div(style='display:flex;',
  plotly::plotlyOutput("general_plot",width = "300px",height="300px"),
  plotly::plotlyOutput("specific_plot",width = "300px",height="300px")
))

server <- function(input, output, session) {
  
  output$general_plot <- renderPlotly({
    
    gdata_long <- pivot_longer(gdata,
                 cols=everything(),
                 names_to = "name",
                 values_to = "value") %>% 
      mutate(mycol=case_when(name==req(input$myselect) ~ 'red',
             TRUE~'blue'))
    print("draw general")
    plot_ly(data=gdata_long,
            x=~name,
            y=~value,
            type="bar",
            color=~I(mycol)) %>% 
      event_register("plotly_click")
  })
  
  output$specific_plot <- renderPlotly({
    gd <- select(gdata,
                 req(input$myselect))
        plot_ly(data=gd,
            y=as.formula(paste0("~",input$myselect)),
            type="bar")
  })
  
  observe({
  d <- event_data("plotly_click")
  if(isTruthy(d))
    updateSelectInput(session=session,
                      inputId = "myselect",
                      selected=d$x)
  print(d)
  
  })
}

shinyApp(ui, server)
1 Like
#4

Thank you, this example answered my question. You shouldn't have "one" reactive to do everything. You need to be explicit with the reactions and which way they connect, cheers!!