使用 plot3d 和 knitr 绘制图例的意外行为

Question

我正在尝试使用knitr使用 rgl 生成一个带有两个 3d 散点图的 html 文档，但是当我尝试向两个图添加图例时遇到了问题。 使用完全相同的代码（从一个块复制并粘贴到另一个块，然后更改要绘制的值），第一个图的图例以 html 方式显示太大。 我生成了一个示例脚本，其中包含与我正在使用的数据类似的数据：

---
title: "example"
output: html_document
---

Example script

# First plot
```{r 1st chunk, webgl=TRUE, echo = FALSE, fig.width=10, fig.height=10}
library(rgl)
knitr::knit_hooks$set(webgl = hook_webgl)
dt <- data.frame(x = runif(70, min = 1, max = 10),
                 y = runif(70, min = -10, max = 1),
                 z = runif(70, min = -20, max = -10), 
                 groups = rep(c("Group1", "Group2", "Group3", "Group4", "Group5", "Group6", "Group7"), each = 10))
plot3d(dt$x, dt$y, dt$z, 
       xlab = "X", ylab = "Y", zlab = "Z",
       type ="n")
grid3d(c("x", "y+", "z"))
legend3d("bottomright",
       c("Group1", "Group2", "Group3", "Group4", "Group5", "Group6", "Group7"),
       col = c(1:7),
       pch = 20,
       bg = "black",
       bty = "n",
       y.intersp = 0.8,
       cex = 1.5)
for (i in seq_along(unique(dt$groups))){
  sub <- dt[dt$groups == unique(dt$groups)[i],]
  pch3d(sub$x, sub$y, sub$z,
        col = i,
        pch = 16,
        radius = 0.2,
        add = T)}
```

This first legend is way too large, while, with the exame same code, for the next plot, the legend is normal size 

# Second plot
```{r 2nd chunk, webgl=TRUE, echo = FALSE, fig.width=10, fig.height=10}
library(rgl)
knitr::knit_hooks$set(webgl = hook_webgl)
dt <- data.frame(x = runif(150, min = 2, max = 20),
                 y = runif(150, min = -20, max = 2),
                 z = runif(150, min = -30, max = -20), 
                 groups = rep(c("Group1", "Group2", "Group3", "Group4", "Group5", "Group6", "Group7", "Group8",
                                "Group9", "Group10", "Group11", "Group12", "Group13", "Group14", "Group15"), each = 10))
plot3d(dt$x, dt$y, dt$z, 
       xlab = "X", ylab = "Y", zlab = "Z",
       type ="n")
grid3d(c("x", "y+", "z"))
legend3d("bottomright",
       c("Group1", "Group2", "Group3", "Group4", "Group5", "Group6", "Group7", "Group8",
         "Group9", "Group10", "Group11", "Group12", "Group13", "Group14", "Group15"),
       col = c(1:15),
       pch = 20,
       bg = "black",
       bty = "n",
       y.intersp = 0.8,
       cex = 1.5)
for (i in seq_along(unique(dt$groups))){
  sub <- dt[dt$groups == unique(dt$groups)[i],]
  pch3d(sub$x, sub$y, sub$z,
        col = i,
        pch = 16,
        radius = 0.2,
        add = T)}
```

任何帮助都感激不尽！

Answer 1

这是一个有点怪异，我看了一下，注意到cex参数（这确实意味着“字符扩大”）在legend3d呼叫不知何故被解释不同的呼叫打电话。 似乎是一个小错误。

但是我也发现你可以通过在每个绘图之前添加一个open3d命令来修复它。 也许这是一个修复？

代码：

---
title: "example"
output: html_document
---

Example script

```{r 0th chunk, webgl=TRUE, echo = FALSE}
library(rgl)
knitr::knit_hooks$set(webgl = hook_webgl)
```

# First plot


```{r 1st chunk, webgl=TRUE, echo = FALSE, fig.width=5, fig.height=5}
glob_cex <- 0.6

open3d()
dt <- data.frame(x = runif(70, min = 1, max = 10),
                 y = runif(70, min = -10, max = 1),
                 z = runif(70, min = -20, max = -10), 
                 groups = rep(c("Group1", "Group2", "Group3", "Group4", "Group5", "Group6", "Group7"), each = 10))
plot3d(dt$x, dt$y, dt$z, 
       xlab = "X", ylab = "Y", zlab = "Z",
       type ="n")
grid3d(c("x", "y+", "z"))
legend3d("bottomright",
       c("Group1", "Group2", "Group3", "Group4", "Group5", "Group6", "Group7"),
       col = c(1:7),
       pch = 20,
       bg = "black",
       bty = "n",
       y.intersp = 0.8,
       cex = 0.8 )
for (i in seq_along(unique(dt$groups))){
  sub <- dt[dt$groups == unique(dt$groups)[i],]
  pch3d(sub$x, sub$y, sub$z,
        col = i,
        pch = 16,
        radius = 0.2,
        add = T)}
```

Legends are now the same size by adding an open3d() command before each plot.

# Second plot
```{r 2nd chunk, webgl=TRUE, echo = FALSE, fig.width=5, fig.height=5}
open3d()
dt <- data.frame(x = runif(150, min = 2, max = 20),
                 y = runif(150, min = -20, max = 2),
                 z = runif(150, min = -30, max = -20), 
                 groups = rep(c("Group1", "Group2", "Group3", "Group4", "Group5", "Group6", "Group7", "Group8",
                                "Group9", "Group10", "Group11", "Group12", "Group13", "Group14", "Group15"), each = 10))
plot3d(dt$x, dt$y, dt$z, 
       xlab = "X", ylab = "Y", zlab = "Z",
       type ="n")
grid3d(c("x", "y+", "z"))
legend3d("bottomright",
       c("Group1", "Group2", "Group3", "Group4", "Group5", "Group6", "Group7", "Group8",
         "Group9", "Group10", "Group11", "Group12", "Group13", "Group14", "Group15"),
       col = c(1:15),
       pch = 20,
       bg = "black",
       bty = "n",
       y.intersp = 0.8,
       cex = 0.8 )
for (i in seq_along(unique(dt$groups))){
  sub <- dt[dt$groups == unique(dt$groups)[i],]
  pch3d(sub$x, sub$y, sub$z,
        col = i,
        pch = 16,
        radius = 0.2,
        add = T)}
```

截屏：

Answer 2

我建议你不要使用webgl=TRUE ，在底部放置一个rglwidget()调用。 这使得文本太大，因为它是从 256x256 rgl 小窗口放大的； 使用r3dDefaults$windowRect <- c(0,0,1000,1000) （或类似的大值）以获得更好的尺寸。

您可能还想在开始时使用options(rgl.useNULL = TRUE) ，这样您就不会在编织时弹出窗口。 这有一个副作用，即允许您将r3dDefaults$windowRect值设置为大于物理屏幕的值。

r3dDefaults$windowRect和options("rgl.useNULL")值应该只需要在文档顶部附近设置一次，除非您明确更改它们，否则将应用于所有以下绘图。