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ggplot进阶之图例系统

ggplot进阶之图例系统#

library(tidyverse)

── Attaching core tidyverse packages ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── tidyverse 2.0.0 ──
✔ dplyr     1.1.4     ✔ readr     2.1.5
✔ forcats   1.0.0     ✔ stringr   1.5.1
✔ ggplot2   3.5.0     ✔ tibble    3.2.1
✔ lubridate 1.9.3     ✔ tidyr     1.3.1
✔ purrr     1.0.2     

── Conflicts ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── tidyverse_conflicts() ──
✖ dplyr::filter() masks stats::filter()
✖ dplyr::lag()    masks stats::lag()
ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errors

mpg %>% 
  ggplot(aes(x = displ, y = hwy, color = factor(cyl)))+
  geom_point()
../_images/977ad17935282d2dfabcb3c6d13a0ce22cdf4cd7300f819fd99d86591aaae574.png

如果想调整图例的样式，可以使用guides()函数，用法类似theme函数, 具体参数为：

  • 要么是字符串 (i.e. "color = colorbar" or "color = legend"),

  • 要么是特定的函数 (i.e. color = guide_colourbar() or color = guide_legend())

image.png

以下 guides() 函数族用于控制图例的外观

  • guide_colorbar(): continuous colors

  • guide_legend(): discrete values (shapes, colors)

  • guide_axis(): control axis text/spacing, add a secondary axis

  • guide_bins(): creates “bins” of values in the legend

  • guide_colorsteps(): makes colorbar discrete

image.png

2 案例详解#

mpg %>% 
  ggplot(aes(x = displ, y = hwy, color = factor(cyl)))+
  geom_point()+
  ggtitle("This is a title")+
  labs(x = "x_displ", y = "y_hwy")+
  guides(color = "legend")
../_images/78755926f8b838ab7cc535f35e19f8923570b77d72ff325499ac28801d89514f.png 
mpg %>%
  ggplot(aes(x = displ, y = hwy, color = factor(cyl))) +
  geom_point() +
  ggtitle("This is my title") +
  labs(x = "x_displ", y = "y_hwy") +
  guides(color = guide_legend(title = "my title",
                              label.hjust = 1))
../_images/7f8340e66aa8ff7458e97e34d91a0f266587a77f076a81eb909040061edbbbfa.png 
mpg %>%
  ggplot(aes(x = displ, y = hwy, color = factor(cyl))) +
  geom_point() +
  ggtitle("This is my title")  +
  labs(x = "x_displ", y = "y_hwy") +
  guides(color = guide_legend(ncol = 4, 
                              title = "my title"))
../_images/82df37790eb914b21930747fde6b626c293add7bdd75c3972dbf08b05935c1fa.png 
mpg %>%
  ggplot() + 
  geom_jitter(aes(x = cty, y = hwy, color = class),
              key_glyph = draw_key_pointrange)+
  guides(color = guide_legend(nrow = 1))+
  theme(legend.position = "top",
        axis.text = element_text(face = "italic", color = "navy"),
        plot.background = element_rect(fill = "#a0d1f2"),
        panel.background = element_blank(),
        panel.grid = element_line(linetype = "dotdash"))
../_images/954af355d1e60d138ffc8eec304b511b538c54cb343fe1e3b8027b0d01db2613.png 
mpg %>%
  ggplot(aes(x = displ, y = hwy, color = factor(cyl))) +
  geom_point() +
  ggtitle("This is my title")  +
  labs(x = "x_displ", y = "y_hwy") +
  guides(color = guide_legend(title = "title is too high",
                              title.position = "top",
                              title.vjust = 5,
                              label.position = "left",
                              label.hjust = 1,
                              label.theme = element_text(size = 15, angle = 0,
                                                         face = "italic",color = "red"),
                              keywidth = 5,
                              reverse = TRUE))
../_images/d8084625fab15f68ec00908031eb041b57245c3cb9c39aa755d9ccc0823b21ee.png

3 删除其中一个图例#

guides(color = "none)

guides(color = guide_none())

mpg %>% 
  ggplot(aes(x = displ, y = hwy, color = class, size = cyl))+
  geom_point()
../_images/9ffbeaf94ddc031aef8760789ce10506e45abe0ccba8a81586a90282a2cdf839.png

比如，我们想删除size这个图例，那么需要这样做

mpg %>% 
  ggplot(aes(x = displ, y = hwy, color = class, size = cyl))+
  geom_point()+
  guides(color = guide_legend("type"),  # keep
         size = "none")                 # remove

mpg %>% 
  ggplot(aes(x = displ, y = hwy, color = class, size = cyl))+
  geom_point()+
  guides(color = guide_legend("class"),  # keep
         size = "none")                 # remove
../_images/a9128b77f7ab694d36f975030ec8447b2b7d1b1cab11749a7b6c3da45f553b54.png ../_images/a936f0f0163599b5c6f9f71f51461b6b432e586b1cb5103ba2bdf06dc442c2a6.png

或者

mpg %>%
  ggplot(aes(x = displ, y = hwy, color = class, size = cyl)) +
  geom_point() +
  guides(color = guide_legend("type"),
         size = guide_none())
../_images/a9128b77f7ab694d36f975030ec8447b2b7d1b1cab11749a7b6c3da45f553b54.png

4 合并图例#

library(tidyverse)
library(palmerpenguins)

penguins %>% 
  ggplot(aes(x = bill_length_mm, y = bill_depth_mm,
             color = body_mass_g, size = body_mass_g))+
  geom_point(alpha = 0.6)+
  scale_color_viridis_c()

Warning message:
“Removed 2 rows containing missing values or values outside the scale range (`geom_point()`).”
../_images/f7e460c434ac1cc7abd6f4cd24a21e42945ca58d7a30936ea2bae440baf801a2.png

这里color 和 size 都使用了body_mass_g映射，我们可以将两者合并

penguins %>% 
  ggplot(aes(x = bill_length_mm, y = bill_depth_mm,
             color = body_mass_g, size = body_mass_g))+
  geom_point(alpha = 0.6)+
  scale_color_viridis_c()+
  guides(color = guide_legend())

Warning message:
“Removed 2 rows containing missing values or values outside the scale range (`geom_point()`).”
../_images/570af6e18b2643643256c3fc71e5906f22d159ca18132299bde2415710a2cce7.png

更直观的方法

penguins %>% 
  ggplot(aes(x = bill_length_mm, y = bill_depth_mm,
             color = body_mass_g, size = body_mass_g))+
  geom_point(alpha = 0.6)+
  scale_color_viridis_c()+
  guides(color = guide_legend(),
         size  = guide_legend())

Warning message:
“Removed 2 rows containing missing values or values outside the scale range (`geom_point()`).”
../_images/570af6e18b2643643256c3fc71e5906f22d159ca18132299bde2415710a2cce7.png

或者

penguins %>% 
  ggplot(aes(x = bill_length_mm, y = bill_depth_mm,
             color = body_mass_g, size = body_mass_g))+
  geom_point(alpha = 0.6)+
  scale_color_viridis_c()+
  guides(color = guide_legend("title"),
         size  = guide_legend("title"))

Warning message:
“Removed 2 rows containing missing values or values outside the scale range (`geom_point()`).”
../_images/cac4cb1c03c9923286b4d91f6fdc942cd8bba5be40e01cf32cbe2a0ce3d8b3e1.png

最省力的是

penguins %>% 
  ggplot(aes(x = bill_length_mm, y = bill_depth_mm,
             color = body_mass_g, size = body_mass_g))+
  geom_point(alpha = 0.6)+
  scale_color_viridis_c(guide = "legend")

Warning message:
“Removed 2 rows containing missing values or values outside the scale range (`geom_point()`).”
../_images/570af6e18b2643643256c3fc71e5906f22d159ca18132299bde2415710a2cce7.png 
mtcars %>%
  as_tibble() %>%
  ggplot(aes(x = wt, y = mpg, shape = factor(vs), color = hp)) +
  geom_point(size = 3) +
  colorspace::scale_color_continuous_sequential(palette = "Dark Mint") +
  scale_shape_discrete(labels = c("V-shaped", "Straight")) +
  labs(
    x = "Weight (1000 lbs)", y = "Miles per gallon",
    title = "Motor Trend Car Road Tests",
    shape = "Engine", color = "Horsepower"
  ) +
  theme(
    text = element_text(size = 18, color = "white"),
    rect = element_rect(fill = "black"),
    panel.background = element_rect(fill = "black"),
    legend.key = element_rect(fill = "black"),
    axis.text = element_text(color = "white"),
    plot.title.position = "plot",
    plot.margin = margin(10, 10, 10, 10)
  ) +
  guides(
    shape =
      guide_legend(override.aes = list(color = "white"))
  )
../_images/6b730df620f53523503768faf70f30ade4e0407d54ac4c013e6a0defdf64cfe9.png
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