为 scale_fill_continuous 连续比例而不是离散制作图例

Question

我正在使用scale_fill_gradientn()的 function ，它通常应该产生一个连续的比例作为图例，但是如果我使用下面附加的代码，结果会产生一个带有颜色框作为离散值的图例

  ggplot(aes(x=grouping,y=person,fill=score)) + 
  geom_tile(stat = "identity",position = "identity",colour="black",size=1) + 
  facet_grid(family~functional,switch = "y") +
  scale_fill_gradientn(colours = c("white","orange","red"),
    limits=c(0,100),breaks = c(0,50,100),labels=c("min","mid","max"),
    guide = guide_legend(direction = "horizontal",title.position = "bottom")) +
    labs(fill = "Average Percentage")

我注意到，只要我从scale_fill_gradientn() function 中删除guide参数，它就会给我一个连续的比例，即

scale_fill_gradientn(colours = c("white","orange","red"),
    limits=c(0,100),breaks = c(0,50,100),labels=c("min","mid","max"))

但是我的问题是为什么会发生这种情况，如果我必须避免使用guide参数，我该如何在刻度周围添加黑色边框（如上图带有离散颜色框的图片）以及调整位置标题和标签 例如，将图例标题放在颜色条下方，将标签放在颜色条上方？ 非常感谢

Answer 1

这是一个潜在的解决方案，使用palmer penguins 数据集作为最小的、可重复的示例：

library(tidyverse)
library(palmerpenguins)

penguins %>% 
  na.omit() %>%
  ggplot(aes(x = body_mass_g, y = bill_length_mm, fill = flipper_length_mm)) +
  geom_point(shape = 21, size = 3) +
  scale_fill_gradientn(colours = c("white", "orange", "red"),
                       limits = c(170, 240), breaks = c(180, 205, 235),
                       labels = c("min", "mid", "max"),
                       guide = guide_legend(direction = "horizontal",
                                            title.position = "bottom"))

penguins %>% 
  na.omit() %>%
  ggplot(aes(x = body_mass_g, y = bill_length_mm, fill = flipper_length_mm)) +
  geom_point(shape = 21, size = 3) +
  scale_fill_gradientn(colours = c("white", "orange", "red"),
                       limits = c(170, 240), breaks = c(180, 205, 235),
                       labels = c("min", "mid", "max"),
                       guide = guide_colourbar(direction = "horizontal",
                                               title.position = "bottom"))

^{由代表 package (v2.0.1) 于 2022 年 7 月 25 日创建}

这能解决你的问题吗？