scattermapbox non-circle marker symbols not shown in legend since v4.12.0

从提供的 R reprex 开始，使用 scattermapbox traces，并比较 plotly 4.11.0 和 4.12.0 之间的图例行为。跟踪 marker 符号如何通过 add_trace 传递，并检查 scattermapbox 的图例处理；当 circle、diamond、square 和 marker 条目能够正确渲染，且不影响 scattergeo 或 scatter 的行为时，即视为完成。

Since upgrading to plotly 4.12.0, only the "circle" symbol is rendered correctly in the legend for scattermapbox traces. Other marker symbols (e.g. "diamond", "square") are no longer displayed — the legend shows a blank entry for those.

v 4.12.0

v 4.11.0

(note that already in previuos versions, the non-circle markers were not shown on the canvas itself, but this was not an issue in our use case, because we only wanted to create the custom legend with the square markers)

reprex

library(plotly)

symbols_to_try <- c(
  "circle",
  "diamond",
  "square",
  "marker"
)

traces <- lapply(seq_along(symbols_to_try), function(i) {
  list(
    type       = "scattermapbox",
    mode       = "markers",
    lon        = i * 2,
    lat        = 51,
    name       = symbols_to_try[i],
    showlegend = TRUE,
    hoverinfo  = "name",
    marker     = list(
      color  = "steelblue",
      size   = 20,
      symbol = symbols_to_try[i]
    )
  )
})

p <- plotly_empty() |>
  layout(
    mapbox = list(
      style  = "carto-positron",
      center = list(lon = 5, lat = 51),
      zoom   = 3
    ),
    legend = list(x = 1, xanchor = "right", y = 1)
  ) |>
  config(displaylogo = FALSE)

for (tr in traces) {
  p <- add_trace(p,
    inherit    = FALSE,
    type       = tr$type,
    mode       = tr$mode,
    lon        = tr$lon,
    lat        = tr$lat,
    name       = tr$name,
    showlegend = tr$showlegend,
    hoverinfo  = tr$hoverinfo,
    marker     = tr$marker
  )
}

p

packageVersion("plotly")

Further info:

The legend (and markers on canvas) work fine with "scattergeo" or even "scatter", but it has other side-effects in our setting that makes the plot be drawn twice, even if setting the layout like

plotly::layout(
    plotly_object,
    geo = list(
      visible = FALSE,
      showframe = FALSE,
      showcoastlines = FALSE,
      showland = FALSE,
      showocean = FALSE
    )
  )