R语言plotly 3D散点图如何为不同轨迹手动设置标记符号与颜色

我使用plot_ly绘制包含三条轨迹（trace）的3D散点图，希望为每条轨迹设置不同的标记符号和灰度颜色：

• 第一条轨迹使用圆形标记
• 第二条使用菱形标记
• 第三条使用倒三角标记
  各自匹配不同的灰度色彩。
  初始实现代码如下：

library(plotrix)
library(plotly)
library(processx)

x <- c(1, 2, 3, 4)
y <- c(2, 4, 6, 8)
z <- c(1, 2, 3, 4)
df <- data.frame(x, y, z)
z1 <- z + 1.5
df1 <- data.frame(x, y, z1)
z2 <- z + 3
df2 <- data.frame(x, y, z2)
symbols <- c("circle", "diamond", 'triangle-down')
colors <- c("gray", "lightgray", "darkslategray")
plot<- plot_ly()%>%
  add_trace(data = df, x = ~x, y = ~y, z = ~z,type = "scatter3d",
    mode = 'markers', marker = list(size = 8, symbol = 1, symbols = symbols, color = 1, colors = colors)) %>%
  add_trace(data = df1, x = ~x, y = ~y, z = ~z1,type = "scatter3d",
            mode = 'markers', marker = list(size = 8, symbol = 2, symbols = symbols, color = 2, colors = colors)) %>%
  add_trace(data = df2, x = ~x, y = ~y, z = ~z2,type = "scatter3d",
            mode = 'markers', marker = list(size = 8, symbol = 8, symbols = symbols, color = 3, colors = colors)) %>%
  layout(title = 'Explore Options')
plot

运行上述代码后并未达到预期效果，所有轨迹均仅显示为不同颜色的圆形标记，未实现符号区分，实际效果如下：

代码参数逻辑存在两个核心错误：

1. symbols和colors参数是给映射到数据列的离散变量做样式匹配用的，单条轨迹单独设置固定样式时不需要传入这两个参数，直接给symbol和color传具体样式值即可
2. 3D散点图的symbol参数不支持数字索引传值，必须直接传入标记名称字符串，传入数字1/2/8时不会被识别为对应符号，会被默认回退为圆形标记。

直接给每条轨迹单独指定固定的标记符号和颜色即可，不需要全局传入symbols/colors映射数组，无关依赖也可以直接移除：

library(plotly)

x <- c(1, 2, 3, 4)
y <- c(2, 4, 6, 8)
z <- c(1, 2, 3, 4)
df <- data.frame(x, y, z)
z1 <- z + 1.5
df1 <- data.frame(x, y, z1)
z2 <- z + 3
df2 <- data.frame(x, y, z2)

plot <- plot_ly()%>%
  add_trace(
    data = df, x = ~x, y = ~y, z = ~z, type = "scatter3d",
    mode = 'markers', 
    marker = list(size = 8, symbol = "circle", color = "gray")
  ) %>%
  add_trace(
    data = df1, x = ~x, y = ~y, z = ~z1, type = "scatter3d",
    mode = 'markers', 
    marker = list(size = 8, symbol = "diamond", color = "lightgray")
  ) %>%
  add_trace(
    data = df2, x = ~x, y = ~y, z = ~z2, type = "scatter3d",
    mode = 'markers', 
    marker = list(size = 8, symbol = "triangle-down", color = "darkslategray")
  ) %>%
  layout(title = 'Explore Options')
plot

运行后即可得到三条分别为圆形（灰色）、菱形（浅灰色）、倒三角（深石板灰）的3D散点轨迹，符合预期效果。

内容的提问来源于stack exchange，提问作者Obromios