Subscript out of bounds error when trying to combine segment and markers with frame

[awgymer]

I am attempting to make an animated dumbbell chart in plotly with R.

Following the example here and using the info here, I came up with the following code:

    df <- data.frame(
      category=c('a', 'b', 'c', 'd', 'a', 'b', 'c', 'd'),
      year=c(2000, 2000, 2000, 2000, 2001, 2001, 2001, 2001),
      val_a=c(1,2,2,1,2,5,6,8),
      val_b=c(3,5,4,7,1,9,2,12)
    )
    
    plot_ly(data = df, frame = ~year) %>%
      add_markers(x = ~val_a, y = ~category, name = "Val_A", color = I("red")) %>%
      add_markers(x = ~val_b, y = ~category, name = "Val_B", color = I("blue")) %>%
      add_segments(x = ~val_a, xend = ~val_b, y = ~category, yend = ~category, showlegend=F) %>%
      layout(
        title = "Val A v Val B",
        xaxis = list(title = "Value"), 
        yaxis = list(title = ""),
        margin = list(l = 65)
    )  

Unfortunately this throws the following error:

    Error in which(idx)[[1]] : subscript out of bounds
    18.
    registerFrames(p, frameMapping = frameMapping)
    17.
    plotly_build.plotly(instance)
    16.
    instance$preRenderHook(instance)
    15.
    createPayload(x)
    14.
    toJSON(createPayload(x))
    13.
    widget_data(x, id)
    12.
    htmltools::tagList(container(htmltools::tagList(x$prepend, widget_html(name = class(x)[1], package = attr(x, "package"), id = id, style = style, class = paste(class(x)[1], "html-widget"), width = sizeInfo$width, height = sizeInfo$height), x$append)), widget_data(x, id), if (!is.null(sizeInfo$runtime)) { ...
    11.
    toHTML(x, standalone = standalone)
    10.
    as.tags.htmlwidget(x, standalone = TRUE)
    9.
    htmltools::as.tags(x, standalone = TRUE)
    8.
    isTag(ui)
    7.
    rewriteTags(x, function(uiObj) { if (isTag(uiObj) || isTagList(uiObj) || is.character(uiObj)) return(uiObj) else return(tagify(as.tags(uiObj))) ...
    6.
    tagify(x)
    5.
    renderTags(html)
    4.
    save_html(html, file = index_html, background = background, libdir = "lib")
    3.
    html_print(htmltools::as.tags(x, standalone = TRUE), viewer = if (view) viewerFunc)
    2.
    print.htmlwidget(x)
    1.
    (function (x, ...) UseMethod("print"))(x)

However, if you run the plot code with either the markers or the segments, it works fine. Why then can I not seem to combine them?

[nitram9]

Just wanted to let you know that I have the same thing happening on my end. Have not yet figured out why both markers and lines work separately but when together, the error is thrown.