如何在R plotly的add_markers()中按分类变量设置标记样式并添加3D面板轮廓线？

1. 修复分类变量的标记颜色与符号不生效问题 #

plotly中针对分类变量的颜色和符号映射，需使用color_discrete_map和symbol_map参数（而非colors和symbols）绑定因子水平与对应样式，确保映射关系正确生效。

2. 添加3D面板的轮廓线 #

通过添加多条3D线条（scatter3d类型，mode='lines'），绘制正卦限立方体的边框，实现附图中的“壁”轮廓效果。

修改后的完整代码 #

# Packages
library(plotly)
library(misc3d)

# Fake data
norm_vec <- function(x) sqrt(sum(x ^ 2)) 
X3d_norm <- data.frame(T3 = runif(100), T6 = runif(100), P4 = runif(100))
norms <- apply(X3d_norm, 1, norm_vec)
X3d_norm <- X3d_norm  / norms
X3d_norm$cluster <- factor(sample(1:2, 100, replace = T), ordered = T)

# Getting octant data
f <- function(x, y, z){x ^ 2 + y ^ 2 + z ^ 2}
R <- 1
x <- y <- z <- seq(0, R, length.out = 100)
g <- expand.grid(x = x, y = y, z = z)
voxel <- array(with(g, f(x, y, z)),dim = c(100, 100, 100))

cont <- computeContour3d(voxel, level = R ^ 2, x = x, y = y, z = z)
idx <- matrix(0:(nrow(cont) - 1), ncol = 3,byrow = TRUE)

# Colors and symbols
pal <- c("#E69F00", "#009E73")
names(pal) <- c("1", "2")  # 确保与因子水平字符串匹配

symb <- c("circle", "square")
names(symb) <- c("1", "2")

# 生成正卦限立方体轮廓线的坐标
cube_edges <- list(
  # x=0平面的四条边
  list(x=rep(0,2), y=c(0,1), z=c(0,0)),
  list(x=rep(0,2), y=c(0,1), z=c(1,1)),
  list(x=rep(0,2), y=c(0,0), z=c(0,1)),
  list(x=rep(0,2), y=c(1,1), z=c(0,1)),
  # y=0平面的四条边
  list(x=c(0,1), y=rep(0,2), z=c(0,0)),
  list(x=c(0,1), y=rep(0,2), z=c(1,1)),
  list(x=c(0,0), y=rep(0,2), z=c(0,1)),
  list(x=c(1,1), y=rep(0,2), z=c(0,1)),
  # z=0平面的四条边
  list(x=c(0,1), y=c(0,0), z=rep(0,2)),
  list(x=c(0,1), y=c(1,1), z=rep(0,2)),
  list(x=c(0,0), y=c(0,1), z=rep(0,2)),
  list(x=c(1,1), y=c(0,1), z=rep(0,2))
)

# Plot
p <- plot_ly() %>%
  add_mesh(
    x = cont[, 1], y = cont[, 2], z = cont[, 3],
    i = idx[, 1], j = idx[, 2], k = idx[, 3],
    opacity = 0.15
  ) %>% 
  add_markers(
    data = X3d_norm,
    x = ~T3, y = ~P4, z = ~T6, 
    color = ~cluster, 
    color_discrete_map = pal,  # 替换为分类颜色映射参数
    symbol = ~cluster, 
    symbol_map = symb,         # 替换为分类符号映射参数
    marker = list(size = 6)    # 可选：调整标记大小
  ) %>% 
  layout(
    legend = list(title = list(text = 'Clusters')),
    scene = list(
      xaxis = list(
        title = "T3", nticks = 4, tickvals = c(0.20, 0.40, 0.60, 0.80), 
        tickfont = list(size = 16), titlefont = list(size = 24)),
      yaxis = list(
        title = "P4", nticks = 4, tickvals = c(0.20, 0.40, 0.60, 0.80),
        tickfont = list(size = 16), titlefont = list(size = 24)),
      zaxis = list(
        title = "T6", nticks = 4, tickvals = c(0.20, 0.40, 0.60, 0.80),
        tickfont = list(size = 16), titlefont = list(size = 24))
    )
  )

# 添加所有立方体轮廓线
for (edge in cube_edges) {
  p <- p %>% add_trace(
    x = edge$x, y = edge$y, z = edge$z,
    type = 'scatter3d', mode = 'lines',
    line = list(color = 'black', width = 2),
    showlegend = FALSE
  )
}

p

关键修改说明 #

• 颜色映射：将colors替换为color_discrete_map，并确保颜色向量的名称与cluster因子的水平字符串完全匹配（因子水平默认是字符串类型，所以用"1"而非1）。
• 符号映射：将symbols替换为symbol_map，同样确保符号向量的名称与因子水平对应。
• 轮廓线：通过循环添加12条3D线条，绘制正卦限立方体的所有边框，线条样式设置为黑色实线，不显示在图例中。

内容的提问来源于stack exchange，提问作者GuerreroAguera