Modify specific plotly trace using plotlyProxy without referencing other traces

Question

I'm targeting a specific plotly trace with my R shiny inputs but I'd like to do so without referring to the data behind all the other traces. As seen below, updating the cylinder trace depends on an else condition. I'd like to avoid that, as in my real data, I have many other traces, rather than the one here (the sphere trace).

library(shiny)
library(plotly)
library(purrr)

plot_cylinder <- function(x, y, z, radius, height, color = 'red') {
  theta <- seq(0, 2*pi, length.out = 30)
  z_cyl <- seq(z, z + height, length.out = 2)
  x_cyl <- outer(x + radius * cos(theta), rep(1, length(z_cyl)))
  y_cyl <- outer(y + radius * sin(theta), rep(1, length(z_cyl)))
  z_cyl <- outer(rep(1, length(theta)), z_cyl)
  
  list(
    type = "surface",
    x = x_cyl,
    y = y_cyl,
    z = z_cyl,
    colorscale = list(c(0, color), c(1, color))
  )
}

plot_sphere <- function(x, y, z, r, color = 'blue') {
  theta <- seq(0, 2*pi, length.out = 30)
  phi <- seq(0, pi, length.out = 30)
  x_sphere <- x + r * outer(cos(theta), sin(phi))
  y_sphere <- y + r * outer(sin(theta), sin(phi))
  z_sphere <- z + r * outer(rep(1, length(theta)), cos(phi))
  
  list(x = x_sphere, y = y_sphere, z = z_sphere, color = color)
}

# Static sphere data
sphere_radius <- 7.24
sphere_data <- plot_sphere(0, 0, 10, sphere_radius)

cylinder_data <- plot_cylinder(0, 0, 0, 3, 10)

ui <- fluidPage(
  titlePanel("Cylinder Plotting"),
  sidebarLayout(
    sidebarPanel(
      sliderInput("radius", "Cylinder Radius:", min = 1, max = 10, value = 3),
      sliderInput("height", "Cylinder Height:", min = 1, max = 20, value = 10),
      actionButton("initialize", "Initialize Cylinder")
    ),
    mainPanel(
      plotlyOutput("plot")
    )
  )
)

server <- function(input, output, session) {
  
  plot <- plot_ly() |> 
    add_surface(x = sphere_data$x, y = sphere_data$y, 
                z = sphere_data$z, colors = sphere_data$color, 
                opacity = 0.5, name = "sphere") |> 
    add_surface(x = cylinder_data$x, y = cylinder_data$y, 
                z = cylinder_data$z, colorscale = cylinder_data$colorscale, 
                opacity = 0, name = "cylinder")
  
  pb <- plotly_build(plot)
  traces <- map(pb$x$data, "name")
  
  output$plot <- renderPlotly({
    plot
  })
  
  observeEvent(input$initialize, {
    proxy <- plotlyProxy("plot", session)
    
    plotlyProxyInvoke(proxy, "restyle", list(
      opacity = lapply(traces, function(name) if(name %in% "cylinder") 0.1 else 0.5)
      ))
  })
  
  observeEvent(c(input$radius, input$height), {
    proxy <- plotlyProxy("plot", session)
    
    # Get the updated cylinder trace
    cylinder_data <- plot_cylinder(0, 0, 0, input$radius, input$height)
    
    # Update the trace with the new x, y, z values
    plotlyProxyInvoke(proxy, "restyle", list(
      x = lapply(traces, function(name) if(name %in% "cylinder") cylinder_data$x else sphere_data$x),
      y = lapply(traces, function(name) if(name %in% "cylinder") cylinder_data$y else sphere_data$y),
      z = lapply(traces, function(name) if(name %in% "cylinder") cylinder_data$z else sphere_data$z)
    ))
  })
}

shinyApp(ui = ui, server = server)

I don't see where traces is defined in your code. Did I miss it? — Stéphane Laurent
– Stéphane Laurent, Commented May 31, 2024 at 8:10
If I get this right you would like to modify the trace by its name? Here is how to get the trace.name / trace.index mapping. — ismirsehregal
– ismirsehregal, Commented May 31, 2024 at 13:04
@ismirsehregal Looks like some packages have changed and made those answers are out-of-date. But how would indices help? Could I do plotlyProxyInvoke(proxy, "restyle", indices, x ...? — its.me.adam
– its.me.adam, Commented May 31, 2024 at 19:28
Yes, plotly's restyle function has a traceIndices parameter. I'm currently short on time, but I'll try to come back here to provide a proper answer. — ismirsehregal
– ismirsehregal, Commented Jun 1, 2024 at 6:07

ismirsehregal · Accepted Answer · 2024-06-04 12:57:19Z

2

Plotly's restyle function has a traceIndices parameter:

An efficient means of changing attributes in the data array in an existing plot. When restyling, you may choose to have the specified changes affect as many traces as desired. The update is given as a single object and the traces that are affected are given as a list of traces indices. Note, leaving the trace indices unspecified assumes that you want to restyle all the traces.

Here is how to update only the data of the first trace (index: 0) via plotlyProxyInvoke:

library(shiny)
library(plotly)
library(purrr)

plot_cylinder <- function(x, y, z, radius, height, color = 'red') {
  theta <- seq(0, 2*pi, length.out = 30)
  z_cyl <- seq(z, z + height, length.out = 2)
  x_cyl <- outer(x + radius * cos(theta), rep(1, length(z_cyl)))
  y_cyl <- outer(y + radius * sin(theta), rep(1, length(z_cyl)))
  z_cyl <- outer(rep(1, length(theta)), z_cyl)
  
  list(
    type = "surface",
    x = x_cyl,
    y = y_cyl,
    z = z_cyl,
    colorscale = list(c(0, color), c(1, color))
  )
}

plot_sphere <- function(x, y, z, r, color = 'blue') {
  theta <- seq(0, 2*pi, length.out = 30)
  phi <- seq(0, pi, length.out = 30)
  x_sphere <- x + r * outer(cos(theta), sin(phi))
  y_sphere <- y + r * outer(sin(theta), sin(phi))
  z_sphere <- z + r * outer(rep(1, length(theta)), cos(phi))
  
  list(x = x_sphere, y = y_sphere, z = z_sphere, color = color)
}

# Static sphere data
sphere_radius <- 7.24
sphere_data <- plot_sphere(0, 0, 10, sphere_radius)

cylinder_data <- plot_cylinder(0, 0, 0, 3, 10)

ui <- fluidPage(
  titlePanel("Cylinder Plotting"),
  sidebarLayout(
    sidebarPanel(
      sliderInput("radius", "Cylinder Radius:", min = 1, max = 10, value = 3),
      sliderInput("height", "Cylinder Height:", min = 1, max = 20, value = 10)
    ),
    mainPanel(
      plotlyOutput("plot")
    )
  )
)

server <- function(input, output, session) {
  
  plotly_object <- plot_ly(colors = sphere_data$color) |> 
    add_surface(x = cylinder_data$x, y = cylinder_data$y, 
                z = cylinder_data$z, colorscale = cylinder_data$colorscale, 
                opacity = 0.5, name = "cylinder") |>
    add_surface(x = sphere_data$x, y = sphere_data$y, 
                z = sphere_data$z,
                opacity = 0.5, name = "sphere")
  
  pb <- plotly_build(plotly_object)
  traces <- unlist(map(pb$x$data, "name"))
  trace_indices <- setNames(seq_along(traces) - 1L, traces)
  
  output$plot <- renderPlotly({
    plotly_object
  })
  
  observeEvent(c(input$radius, input$height), {
    proxy <- plotlyProxy("plot", session)
    
    # Get the updated cylinder trace
    cylinder_data <- plot_cylinder(0, 0, 0, input$radius, input$height)
    # Update the trace with the new x, y, z values
    plotlyProxyInvoke(proxy, "restyle", list(
      x = list(cylinder_data$x),
      y = list(cylinder_data$y),
      z = list(cylinder_data$z)
    ), trace_indices[["cylinder"]])
    # if you need to modify multiple traces at once (and leave others as they are):
    # plotlyProxyInvoke(proxy, "restyle", list(
    #   x = list(cylinder_data$x, sphere_data$x + 100L),
    #   y = list(cylinder_data$y, sphere_data$y + 100L),
    #   z = list(cylinder_data$z, sphere_data$z + 100L)
    # ), list(0L, 1L))
  })
}

shinyApp(ui = ui, server = server)

edited Jun 4, 2024 at 12:57

answered Jun 4, 2024 at 8:04

ismirsehregal

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5 Comments

its.me.adam Over a year ago

May you add the index to trace-name mapping from the answer you provided above? I have many traces so I cannot select them simply by number like 0L.

ismirsehregal Over a year ago

Just use the plotly_build approach shown in your example. Please see my edit.

its.me.adam Over a year ago

Thanks! How would you approach it in a case where plotly_build does not give back all traces? Specifically ones added with plotlyProxyInvoke("addTraces"?

ismirsehregal Over a year ago

Dynamically updating the trace name / trace index mapping will require a updated JS solution (not necessary regarding your example). I don't know yet. I will update my earlier answer once I have a solution. Not sure when I'll have the time to dig into this again.

ismirsehregal Over a year ago

@its.me.adam I just updated my earlier answer with another approach of extracting the trace name / trace index mapping.

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