使用 "empty" 插槽格式化行中的 ggplot2 图例文本

Question

我正在尝试在下面的图中格式化图例。这是一些虚拟数据和我的代码：

df <- data.frame(supplement = c("Control", 
                            "0.5 mM NA", "5 mM NA", "10 mM NA",
                            "0.5 mM NI", "5 mM NAI", "10 mM NI"),
             axis1 = c(1, 2, 3, 4, 5, 6, 7),
             axis2 = c(7, 6, 5, 4, 3, 2, 1))

df %>%
  mutate(supplement = factor(supplement,
                             levels = c("Control", 
                                        "0.5 mM NA", "5 mM NA", "10 mM NA",
                                        "0.5 mM NI", "5 mM NAI", "10 mM NI"))) %>%
  ggplot(aes(x = axis1, y = axis2)) +
  geom_point(aes(color = supplement), size = 4) +
  labs(y = "Axis 2",
       x = "Axis 1") +
  scale_colour_manual(name = "",
                      breaks = c("Control", 
                                 "0.5 mM NA", "5 mM NA", "10 mM NA",
                                 "0.5 mM NI", "5 mM NAI", "10 mM NI"),
                      labels = c("No Treatment",
                                 "0.5 mM Nitrate", "5 mM Nitrate", "10 mM Nitrate",
                                 "0.5 mM Nitrite", "5 mM Nitrite", "10 mM Nitrite"),
                      values =  c("#003F5C",
                                  "#824ED4", "#31B3F7", "#FFA600",
                                  "#ABF13D", "#DC267F", "#16F5E3"))+
  guides(color = guide_legend(order = 1, nrow = 2, byrow = TRUE)) +
  theme(legend.title = element_blank(),
        legend.text = element_text(size = unit(14, "pt")),
        legend.position = "bottom",
        legend.box = "vertical",
        axis.title = element_text(size = unit(16, "pt")),
        axis.text = element_text(size = unit(14, "pt")),
        legend.key.size = unit(25, "pt"),
        legend.key.width = unit(0, 'mm'))

我得到的是这个

但我真的很希望他们是这样的。但是我不知道这在 ggplot 中是否可行，因为我还没有找到任何可以做到这一点的东西。

Answer 1

我不知道有任何 (non-complicated) 方法可以将一个特定的图例键与另一行进行比较，但在这种情况下，由于图例中有 7 个项目，您可以通过将指南限制为 3 列并在 scale_color_manual() 中重新排序以将控件放在最后来分离出“No Treatment”键。

在这种情况下，您的情节代码部分将更改为：

# ... original plot code...
scale_colour_manual(name = "",
                      breaks = c( 
                                 "0.5 mM NA", "5 mM NA", "10 mM NA",
                                 "0.5 mM NI", "5 mM NAI", "10 mM NI", "Control"),
                      labels = c(
                                 "0.5 mM Nitrate", "5 mM Nitrate", "10 mM Nitrate",
                                 "0.5 mM Nitrite", "5 mM Nitrite", "10 mM Nitrite", "No Treatment"),
                      values =  c(
                                  "#824ED4", "#31B3F7", "#FFA600",
                                  "#ABF13D", "#DC267F", "#16F5E3", "#003F5C"))+
  guides(color = guide_legend(order = 1, ncol = 3, byrow = TRUE)) +

# ... remaining plot code

另一种方法是使用您的原始代码，只将图例放在绘图的右侧或左侧。为此，删除 guides(...) 行和 legend.position= 主题元素，因为默认设置是放在右边。

Answer 2

如果您可以摆脱图例键背景，那么一种选择是

在guide_legend

ncols=3

向您的因素添加两个额外的类别以向图例添加两个额外的槽或键
将这些类别的标签设置为空字符串，颜色等于绘图背景颜色
此外，我们必须将 drop=FALSE 设置为 scale_color_manual，这样这些未使用的类别就不会被丢弃

library(ggplot2)
library(dplyr)

df <- df %>%
  mutate(supplement = factor(supplement,
                             levels = c("Control", "foo", "bar",
                                        "0.5 mM NA", "5 mM NA", "10 mM NA",
                                        "0.5 mM NI", "5 mM NAI", "10 mM NI")))

ggplot(df, aes(x = axis1, y = axis2)) +
  geom_point(aes(color = supplement), size = 4) +
  labs(y = "Axis 2", x = "Axis 1") +
  scale_colour_manual(name = "",
                      breaks = c("Control", "foo", "bar",
                                 "0.5 mM NA", "5 mM NA", "10 mM NA",
                                 "0.5 mM NI", "5 mM NAI", "10 mM NI"),
                      labels = c("No Treatment", "", "",
                                 "0.5 mM Nitrate", "5 mM Nitrate", "10 mM Nitrate",
                                 "0.5 mM Nitrite", "5 mM Nitrite", "10 mM Nitrite"),
                      values =  c("#003F5C", "white", "white",
                                  "#824ED4", "#31B3F7", "#FFA600",
                                  "#ABF13D", "#DC267F", "#16F5E3"),
                      drop = FALSE) +
  guides(color = guide_legend(order = 1, ncol = 3, byrow = TRUE)) +
  theme(legend.title = element_blank(),
        legend.text = element_text(size = unit(14, "pt")),
        legend.position = "bottom",
        legend.box = "vertical",
        legend.key = element_rect(fill = NA), 
        axis.title = element_text(size = unit(16, "pt")),
        axis.text = element_text(size = unit(14, "pt")),
        legend.key.size = unit(25, "pt"),
        legend.key.width = unit(0, 'mm'))

使用 "empty" 插槽格式化行中的 ggplot2 图例文本

Formatting ggplot2 legend text in rows with "empty" slots

r

ggplot2

legend