ggplot2 theme elements reference

Dongbei University of Finance & Economics

Abstract

ggplot2 is one of the most powerful packages in r for data visualizations and it is essential to master the underlying grammar of graphics to fully utilize its power. While the theming system of ggplot2 allows you to customize the appearance of the plot according to our needs in practice, it is always a frustration to identify the elements on the plot you want to change as you may find it difficult to remember the element names and their corresponding functions to modify, at least this is the case for me.

1 加载经常用的R包

library(pacman)
# 读数据
p_load(readxl,writexl,data.table,openxlsx,haven,rvest)

# 数据探索
p_load(tidyverse,DT,skimr,DataExplorer,explore,vtable,stringr,kableExtra,lubridate)

# 模型
p_load(grf,glmnet,caret,tidytext,fpp2,forecast,car,tseries,hdm,tidymodels,broom)

# 可视化
p_load(patchwork,ggrepel,ggcorrplot,gghighlight,ggthemes,shiny)

# 其它常用包
p_load(magrittr,listviewer,devtools,here,janitor,reticulate,jsonlite)

2 Theme Elements Reference

knitr::include_graphics(here::here("EZ9KYESUYAAzxpg.png"))

knitr::include_graphics(here::here("theme_elements.png"))

3 基础图形

mpg$class %>% unique()

## [1] "compact"    "midsize"    "suv"        "2seater"    "minivan"   
## [6] "pickup"     "subcompact"

mpg %>% 
  filter(class != "2seater",
         manufacturer  %in% c("toyota", "volkswagen")) -> mpg_df

mpg_df %>% str()

## tibble [61 x 11] (S3: tbl_df/tbl/data.frame)
##  $ manufacturer: chr [1:61] "toyota" "toyota" "toyota" "toyota" ...
##  $ model       : chr [1:61] "4runner 4wd" "4runner 4wd" "4runner 4wd" "4runner 4wd" ...
##  $ displ       : num [1:61] 2.7 2.7 3.4 3.4 4 4.7 2.2 2.2 2.4 2.4 ...
##  $ year        : int [1:61] 1999 1999 1999 1999 2008 2008 1999 1999 2008 2008 ...
##  $ cyl         : int [1:61] 4 4 6 6 6 8 4 4 4 4 ...
##  $ trans       : chr [1:61] "manual(m5)" "auto(l4)" "auto(l4)" "manual(m5)" ...
##  $ drv         : chr [1:61] "4" "4" "4" "4" ...
##  $ cty         : int [1:61] 15 16 15 15 16 14 21 21 21 21 ...
##  $ hwy         : int [1:61] 20 20 19 17 20 17 29 27 31 31 ...
##  $ fl          : chr [1:61] "r" "r" "r" "r" ...
##  $ class       : chr [1:61] "suv" "suv" "suv" "suv" ...

mpg_df

p <- mpg_df %>% 
  ggplot(aes(displ,hwy,col = factor(cyl))) +
  geom_point() +
  facet_grid(manufacturer ~ class) +
  labs(title = "hwy vs. displ") +
  scale_color_discrete(name = "Cylinders") +
  mytheme

p 

4 plot元素

p1 <- p + 
  theme(plot.background = element_rect(fill = "lemonchiffon",
                                       color = "black",
                                       size = 2),
        plot.title = element_text(hjust = 0.5, colour = "red", face = "bold"),
        plot.margin = margin(20, 20, 20, 20))
p1

5 Axis元素

p2 <- p1 + theme(axis.line = element_line(colour = "yellow", size = 1),
                 axis.text = element_text(colour = "red"),
                 axis.ticks = element_line(colour = "purple", size = 1))
p2

6 Legend元素

p3 <- p2 + theme(legend.background = element_rect(fill =  "deepskyblue2"),
                 legend.key = element_rect(fill = "lemonchiffon"),
                 legend.title = element_text(colour = "white", face = "bold"),
                 legend.text = element_text(colour = "blue"),
                 legend.margin = margin(10, 10, 10, 10))
p3

7 Panel元素

p4 <- p3 + theme(panel.background = element_rect(fill = "lightblue"),
      panel.grid = element_line(colour = "grey60", size = 0.2),
      panel.border = element_rect(colour = "black", fill = NA))
 
p4

8 Facetting Elements

p5 <- p4 + theme(strip.background = element_rect(fill = "steelblue"),
      strip.text = element_text(colour = "white"),
      panel.spacing = unit(0.3, "in"))
 
p5

9 Final Notes

从示例中可以看到，要修改plot中的单个元素，只需遵循参数: theme(element.name = element function())。这个例子中的最后一个图并不一定很漂亮，因为我使得识别相应的元素变得更加容易。