第 14 章 ggplot2之主题设置

这一章我们一起学习ggplot2中的theme elements 语法,感谢Henry Wang提供了很好的思路。如果需要详细了解,可以参考Hadley Wickham最新版的《ggplot2: Elegant Graphics for Data Analysis》,最推荐的是ggplot2官方文档

theme(element_name = element_function())

这里element_function()有四个

element_text()
element_line()
element_rect()
element_blank()

望文生义吧,内置元素函数有四个基础类型:

  • element_text(), 文本,一般用于控制标签和标题的字体风格
  • element_line(), 线条,一般用于控制线条或线段的颜色或线条类型
  • element_rect(), 矩形区域,一般用于控制背景矩形的颜色或者边界线条类型
  • element_blank() , 空白,就是不分配相应的绘图空间,即删去这个地方的绘图元素。

每个元素函数都有一系列控制外观的参数,下面我们通过具体的案例来一一介绍吧。

library(tidyverse)

还是用让人生厌的ggplot2::mpg数据包吧,具体介绍请见?? 章。

glimpse(mpg)
## Rows: 234
## Columns: 11
## $ manufacturer <chr> "audi", "audi", "audi", "audi...
## $ model        <chr> "a4", "a4", "a4", "a4", "a4",...
## $ displ        <dbl> 1.8, 1.8, 2.0, 2.0, 2.8, 2.8,...
## $ year         <int> 1999, 1999, 2008, 2008, 1999,...
## $ cyl          <int> 4, 4, 4, 4, 6, 6, 6, 4, 4, 4,...
## $ trans        <chr> "auto(l5)", "manual(m5)", "ma...
## $ drv          <chr> "f", "f", "f", "f", "f", "f",...
## $ cty          <int> 18, 21, 20, 21, 16, 18, 18, 1...
## $ hwy          <int> 29, 29, 31, 30, 26, 26, 27, 2...
## $ fl           <chr> "p", "p", "p", "p", "p", "p",...
## $ class        <chr> "compact", "compact", "compac...

稍微做点数据整理

df <- mpg %>% 
  as_tibble() %>% 
  filter(class != "2seater", manufacturer %in% c("toyota", "volkswagen"))
df
## # A tibble: 61 x 11
##    manufacturer model displ  year   cyl trans drv  
##    <chr>        <chr> <dbl> <int> <int> <chr> <chr>
##  1 toyota       4run~   2.7  1999     4 manu~ 4    
##  2 toyota       4run~   2.7  1999     4 auto~ 4    
##  3 toyota       4run~   3.4  1999     6 auto~ 4    
##  4 toyota       4run~   3.4  1999     6 manu~ 4    
##  5 toyota       4run~   4    2008     6 auto~ 4    
##  6 toyota       4run~   4.7  2008     8 auto~ 4    
##  7 toyota       camry   2.2  1999     4 manu~ f    
##  8 toyota       camry   2.2  1999     4 auto~ f    
##  9 toyota       camry   2.4  2008     4 manu~ f    
## 10 toyota       camry   2.4  2008     4 auto~ f    
## # ... with 51 more rows, and 4 more variables:
## #   cty <int>, hwy <int>, fl <chr>, class <chr>

我相信这种图你们已经会画了吧

df %>%
  ggplot(aes(x = displ, y = hwy, color = factor(cyl))) +
  geom_point() +
  facet_grid(vars(manufacturer), vars(class)) +
  ggtitle("这是我的标题") +
  labs(x = "x_displ", y = "y_hwy")

想让这张图,符合你的想法?如何控制呢?come on

14.1 图表整体元素

图表整体元素包括:

描述 主题元素 类型
整个图形背景 plot.background element_rect()
图形标题 plot.title element_text()
图形边距 plot.margin margin()
df %>%
  ggplot(aes(x = displ, y = hwy, color = factor(cyl))) +
  geom_point() +
  facet_grid(vars(manufacturer), vars(class)) +
  ggtitle("这是我的标题") +
  labs(x = "x_displ", y = "y_hwy") +
  theme(
    plot.background = element_rect(fill = "orange", color = "black", size = 10),
    plot.title = element_text(hjust = 1, color = "red", face = "italic"),
    plot.margin = margin(t = 20, r = 20, b = 20, l = 20, unit = "pt")
  )

14.2 坐标轴元素

坐标轴元素包括:

描述 主题元素 类型
坐标轴刻度 axis.ticks element_line()
坐标轴标题 axis.title element_text()
坐标轴标签 axis.text element_text()
直线和坐标轴 axis.line element_line()
df %>%
  ggplot(aes(x = displ, y = hwy, color = factor(cyl))) +
  geom_point() +
  facet_grid(vars(manufacturer), vars(class)) +
  ggtitle("这是我的标题") +
  labs(x = "x_displ", y = "y_hwy") +
  theme(
    axis.line = element_line(color = "orange", size = 2),
    axis.title = element_text(color = "red", face = "italic"),
    axis.ticks = element_line(color = "purple", size = 3),
    axis.text = element_text(color = "blue"),
    axis.text.x = element_text(angle = 45, hjust = 1)
  )

14.3 面板元素

面板元素包括:

描述 主题元素 类型
面板背景 panel.background element_rect()
面板网格线 panel.grid element_line()
面板边界 panel.border element_rect()
df %>%
  ggplot(aes(x = displ, y = hwy, color = factor(cyl))) +
  geom_point() +
  facet_grid(vars(manufacturer), vars(class)) +
  ggtitle("这是我的标题") +
  labs(x = "x_displ", y = "y_hwy") +
  theme(
    panel.background = element_rect(fill = "orange", color = "red"),
    panel.grid = element_line(color = "grey80", size = 0.5)
  )

或者

df %>%
  ggplot(aes(x = displ, y = hwy, color = factor(cyl))) +
  geom_point() +
  facet_grid(vars(manufacturer), vars(class)) +
  ggtitle("这是我的标题") +
  labs(x = "x_displ", y = "y_hwy") +
  theme(
    panel.background = element_rect(fill = "orange"),
    panel.grid = element_line(color = "grey80", size = 0.5),
    panel.border = element_rect(color = "red", fill = NA)
  )

14.4 图例元素

图例元素包括:

描述 主题元素 类型
图例背景 legend.background element_rect()
图例符号 legend.key element_rect()
图例标签 legend.text element_text()
图例标题 legend.title element_text()
图例边距 legend.margin margin
图例位置 legend.postion “top”, “bottom”, “left”, “right”
df %>%
  ggplot(aes(x = displ, y = hwy, color = factor(cyl))) +
  geom_point() +
  facet_grid(vars(manufacturer), vars(class)) +
  ggtitle("这是我的标题") +
  labs(x = "x_displ", y = "y_hwy") +
  theme(
    legend.background = element_rect(fill = "orange"),
    legend.title = element_text(color = "blue", size = 10),
    legend.key = element_rect(fill = "grey80"),
    legend.text = element_text(color = "red"),
    legend.margin = margin(t = 20, r = 20, b = 20, l = 20, unit = "pt"),
    legend.position = "bottom"
  )

14.5 分面元素

分面元素包括:

描述 主题元素 类型
分面标签背景 strip.background element_rect()
条状文本 strip.text element_text()
分面间隔 panel.spacing unit
df %>%
  ggplot(aes(x = displ, y = hwy, color = factor(cyl))) +
  geom_point() +
  facet_grid(vars(manufacturer), vars(class)) +
  ggtitle("这是我的标题") +
  labs(x = "x_displ", y = "y_hwy") +
  theme(
    strip.background = element_rect(fill = "orange"),
    strip.text = element_text(color = "red"),
    panel.spacing = unit(0.3, "inch") # ,
    # strip.switch.pad.grid =
  )

14.6 案例

diamonds %>%
  ggplot(aes(carat, price)) +
  geom_hex() +
  labs(title = "Diamond") +
  theme(
    axis.title.x = element_text(
      size = 30,
      color = "red",
      face = "bold",
      angle = 10
    ),
    legend.title = element_text(
      size = 25,
      color = "#ff6361",
      margin = margin(b = 5)
    ),
    plot.title = element_text(
      size = 35,
      face = "bold",
      color = "blue"
    )
  )

你肯定不会觉得这图好看。

library(palmerpenguins)
penguins %>%
  ggplot(aes(bill_length_mm, bill_depth_mm)) +
  geom_point() +
  theme(
    axis.line.y = element_line(
      color = "black",
      size = 1.2,
      arrow = grid::arrow()
    ),
    axis.line.x = element_line(
      linetype = "dashed",
      color = "brown",
      size = 1.2
    ),
    axis.ticks = element_line(color = "red", size = 1.1),
    axis.ticks.length = unit(3, "mm"),
    panel.grid.major = element_line(
      color = "blue",
      size = 1.2
    ),
    panel.grid.minor = element_line(
      color = "#58508d",
      size = 1.2,
      linetype = "dotted"
    )
  )

penguins %>%
  ggplot(aes(bill_length_mm, bill_depth_mm)) +
  geom_point(aes(color = species)) +
  theme(
    legend.background = element_rect(
      fill = "#fff6c2",
      color = "black",
      linetype = "dashed"
    ),
    legend.key = element_rect(fill = "grey", color = "brown"),
    panel.background = element_rect(
      fill = "#005F59",
      color = "red", size = 3
    ),
    panel.border = element_rect(
      color = "black",
      fill = "transparent",
      linetype = "dashed", size = 3
    ),
    plot.background = element_rect(
      fill = "#a1dce9",
      color = "black",
      size = 1.3
    ),
    legend.position = "bottom"
  )

14.7 小结

14.8 提问

  • ggplot2中 plot 与 panel 有区别?

  • 假定数据是这样

library(tidyverse)
set.seed(12)

d1 <- data.frame(x = rnorm(50, 10, 2), type = "Island #1")
d2 <- data.frame(x = rnorm(50, 18, 1.2), type = "Island #2")

dd <- bind_rows(d1, d2) %>%
  set_names(c("Height", "Location"))

head(dd)
##   Height  Location
## 1  7.039 Island #1
## 2 13.154 Island #1
## 3  8.087 Island #1
## 4  8.160 Island #1
## 5  6.005 Island #1
## 6  9.455 Island #1

你画图后,交给老板看

dd %>%
  ggplot(aes(x = Height, fill = Location)) +
  geom_histogram(binwidth = 1, color = "white") +
  scale_fill_manual(values = c("green3", "turquoise3"))

然而,老板有点不满意,希望你要这样改

请用前后两章学到的内容让老板满意吧