主题(Legend.key=Element_RECT(Fill=&Quot；White&Quot；))不起作用

一种可能的 Select 是不添加填充 colored颜色 (使用show.legend = FALSE)，例如

library(tidyverse)

set.seed(123)
df <- data.frame(
  var_a = rnorm(800),
  var_b = rnorm(800),
  criteria = rep(c("a", "b", "c", "d", "e", "f", "g", "h"), each = 100)
)



ggplot(df, aes(var_a, var_b)) +
  stat_density_2d(aes(fill = after_stat(level)), geom = "polygon",
                  show.legend = FALSE)+
  scale_fill_distiller(palette=1, direction=-1)+
  geom_smooth(aes(color = criteria), method = "lm", se = FALSE) +
  geom_abline(slope=1, intercept=0, color = "gray35", lwd = 0.3)+
  ylab("x label")+
  xlab("y_label")+
  xlim(-4, 4)+
  ylim(-4, 4)
#> `geom_smooth()` using formula = 'y ~ x'

^{创建于2024-02-05年第reprex v2.1.0页}

另一种 Select 是自己指定key_glyph(按https://ggplot2.tidyverse.org/reference/draw_key.html)，例如

library(tidyverse)

set.seed(123)
df <- data.frame(
  var_a = rnorm(800),
  var_b = rnorm(800),
  criteria = rep(c("a", "b", "c", "d", "e", "f", "g", "h"), each = 100)
)

ggplot(df, aes(var_a, var_b)) +
  stat_density_2d(aes(fill = after_stat(level)), geom = "polygon",
                  key_glyph = "path")+
  scale_fill_distiller(palette=1, direction=-1)+
  geom_smooth(aes(color = criteria), method = "lm", se = FALSE) +
  geom_abline(slope=1, intercept=0, color = "gray35", lwd = 0.3)+
  ylab("x label")+
  xlab("y_label")+
  xlim(-4, 4)+
  ylim(-4, 4)
#> `geom_smooth()` using formula = 'y ~ x'

^{创建于2024-02-05年第reprex v2.1.0页}

或者如果你想要一些不同的东西，你可以制作你自己的字形，例如

library(tidyverse)

set.seed(123)
df <- data.frame(
  var_a = rnorm(800),
  var_b = rnorm(800),
  criteria = rep(c("a", "b", "c", "d", "e", "f", "g", "h"), each = 100)
)

draw_key_stat_2d <- function(data, params, size) {
  if (is.null(data$linewidth)) {
    data$linewidth <- 0.5
  }
  
  lwd <- min(data$linewidth, min(size) / 4)
  
  rectGrob(
    width = unit(1, "npc") - unit(lwd, "mm"),
    height = unit(1, "npc") - unit(lwd, "mm"),
    gp = gpar(
      col = "grey20" %||% NA,
      fill = radialGradient(colours = c("#00000000", "deepskyblue"),
                            r1 = 0.2, r2 = 0.8) %||% "grey20", 
      lty = data$linetype %||% 1,
      lwd = lwd * .pt,
      linejoin = params$linejoin %||% "mitre",
      lineend = params$lineend %||% "butt"
    ))
}

library(grid)
library(gridExtra)
#> 
#> Attaching package: 'gridExtra'
#> The following object is masked from 'package:dplyr':
#> 
#>     combine
ggplot(df, aes(var_a, var_b)) +
  stat_density_2d(aes(fill = after_stat(level)), geom = "polygon",
                  key_glyph = draw_key_stat_2d)+
  scale_fill_distiller(palette=1, direction=-1)+
  geom_smooth(aes(color = criteria), method = "lm", se = FALSE) +
  geom_abline(slope=1, intercept=0, color = "gray35", lwd = 0.3)+
  ylab("x label")+
  xlab("y_label")+
  xlim(-4, 4)+
  ylim(-4, 4)
#> `geom_smooth()` using formula = 'y ~ x'

^{创建于2024-02-05年第reprex v2.1.0页}