movable lines in plot

[Felipe3]

Hi

I am trying to add movable lines to my plots in shiny. I did find this example that works well:

Moveable Vertical Lines in a Shiny App

Hi there, So I was reading this post, linked here and I was able to make my plot with a moveable vertical line! However, when I move the vertical line, the new point where the vertical line and my plot intercept does not update. I've attached a GIF showing what happens when I move the vertical line. [Screen-Recording-2020-06-04-at-9.05.15-PM] Also, here is the code that I used, and I had to make some slight modifications to what was originally done in the first post in order for the code to run. Perhaps my changes have caused some issues, but this is the only way that I was able to produce a vertical bar correctly. Also, I put it inside of an eventReactive, because I only want the plot t…

Now I want to be able to add two or more lines to the plot, so I adapted the code, but I am only able to see one.

Here is my code :

library(shiny)
library(plotly)
ui <- fluidPage(
  plotlyOutput("new_plot")
)

server <- function(input, output, session) {
  s <-reactive({
    
    rv <- reactiveValues(x = NULL, y = NULL)
    
    rv$x <- as.vector(-50:50)
    rv$y <- as.vector(rv$x^2)
    
    d <- event_data("plotly_relayout", source = "trajectory")
    
    selected_point <- if (!is.null(d[["shapes[0].x0"]])) {
      xint <- d[["shapes[0].x0"]]
      xpt <- rv$x[which.min(abs(rv$x - xint))]
      list(x = xpt, y = rv$y[which.min(abs(rv$x - xint))])
    } else {
      list(x = -40, y = rv$y[which(rv$x == min(rv$x))])
    }
    
    d2 <- event_data("plotly_relayout", source = "trajectory")
    
    selected_point2 <- if (!is.null(d2[["shapes[0].x0"]])) {
      xint <- d2[["shapes[0].x0"]]
      xpt <- rv$x[which.min(abs(rv$x - xint))]
      list(x = xpt, y = rv$y[which.min(abs(rv$x - xint))])
    } else {
      list(x = -20, y = rv$y[which(rv$x == min(rv$x))])
    }
    
    print(selected_point)
    
    
    plot_ly(color = I("red"), source = "trajectory") %>%
      add_lines(x = rv$x, y = rv$y) %>%
      add_markers(x = selected_point$x, y = selected_point$y) %>%
      layout(
        shapes = list(
          type = "line", 
          line = list(color = "gray", dash = "dot"),
          x0 = selected_point$x, 
          x1 = selected_point$x,
          y0 = 0,
          y1 = 1,
          yref = "paper"
        )
      ) %>%
      add_markers(x = selected_point2$x, y = selected_point2$y) %>%
      layout(
        shapes = list(
          type = "line", 
          line = list(color = "blue", dash = "dot"),
          x0 = selected_point2$x, 
          x1 = selected_point2$x,
          y0 = 0,
          y1 = 1,
          yref = "paper"
        )
      ) %>%
      
      config(editable = TRUE)
  })
  
  output$new_plot <- renderPlotly({
    s()
  })
}

shinyApp(ui = ui, server = server)

Many thanks !

[scottyd22]

Welcome to the community @Felipe3! Based on some experimentation, I found the lines will appear if you put both of them within shapes = list(), making a"list of lists".

plot_ly(color = I("red"), source = "trajectory") %>%
      add_lines(x = rv$x, y = rv$y) %>%
      add_markers(x = selected_point$x, y = selected_point$y) %>%
      add_markers(x = selected_point2$x, y = selected_point2$y) %>%
      layout(
        shapes = list(
          list(type = "line", 
               line = list(color = "gray", dash = "dot"),
               x0 = selected_point$x, 
               x1 = selected_point$x,
               y0 = 0,
               y1 = 1,
               yref = "paper"),
          list(type = "line",
               line = list(color = "blue", dash = "dot"),
               x0 = selected_point2$x,
               x1 = selected_point2$x,
               y0 = 0,
               y1 = 1,
               yref = 'paper')
        )
      ) %>%
      config(editable = T)

[Felipe3]

Thanks Scotty for your answer . Try the code and I am able to see the lines, but when I try to move them, they come back to their original position. Any idea on how to solve that ?

Many thanks !

[scottyd22]

You're welcome, and I noticed that too. I think it may have something to do with the "plotly_relayout" specification, but I'm not familiar with the event_data() function. Maybe someone with more experience in this area can provide guidance on the issue.