ggplot绘图修改图例标题及图例取值标签的问题咨询

我正在使用ggplot绘制图表，想要修改图例的标题以及图例上展示的取值标签，尝试了现有常用的修改方法均未生效。

示例数据集结构 #

structure(list(sold_date_yq = structure(c(2014.5, 2014.75, 2014.75, 
2015, 2015, 2015.25, 2015.25, 2015.5, 2015.5, 2015.75, 2015.75, 
2016, 2016, 2016.25, 2016.25, 2016.5), class = "yearqtr"), V_tour_update = c(1, 
0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0), average_sold_sqft = c(646.354142011834, 
623.121985926505, 678.629387755102, 651.493616045845, 666.909525139665, 
671.250383912249, 680.049114583333, 698.693468862584, 699.523971830986, 
718.077661016949, 759.139753521127, 791.252619047619, 814.418133704735, 
836.438735902256, 884.5826, 849.757720754717)), row.names = c(NA, 
-16L), groups = structure(list(sold_date_yq = structure(c(2014.5, 
2014.75, 2015, 2015.25, 2015.5, 2015.75, 2016, 2016.25, 2016.5
), class = "yearqtr"), .rows = structure(list(1L, 2:3, 4:5, 6:7, 
    8:9, 10:11, 12:13, 14:15, 16L), ptype = integer(0), class = c("vctrs_list_of", 
"vctrs_vctr", "list"))), row.names = c(NA, 9L), class = c("tbl_df", 
"tbl", "data.frame"), .drop = TRUE), class = c("grouped_df", 
"tbl_df", "tbl", "data.frame"))

现有绘图代码 #

ggplot(a, aes(x=sold_date_yq, y=average_sold_sqft)) +
  geom_line(aes(color=as.factor(V_tour_update)), size = 1) + scale_x_yearqtr(format="%YQ%q",n=6) + scale_y_continuous(limits = c(300,1200))+ 
  theme(legend.position="right")+
  theme(plot.title = element_text(hjust = 0.5, size=10))+
  theme_bw()+ theme(axis.text.x = element_text(angle = 90, vjust=0, hjust=1))+
  theme(legend.position=c(0.8, 0.1))

需求说明 #

我希望能够同时修改图例的标题，以及将图例中默认显示的0和1替换为自定义的说明文本，当前代码生成的结果图如下：

你之前的方法失效主要有两个原因：一是theme_bw()放在了自定义theme配置之后，会重置前面的主题参数；二是没有针对color对应的映射修改图例配置，你可以直接通过scale_color_discrete一步实现图例标题和标签的修改，修改后的参考代码如下：

library(ggplot2)
library(zoo)

ggplot(a, aes(x=sold_date_yq, y=average_sold_sqft)) +
  geom_line(aes(color=as.factor(V_tour_update)), size = 1) + 
  scale_x_yearqtr(format="%YQ%q",n=6) + 
  scale_y_continuous(limits = c(300,1200)) +
  # 修改图例标题和标签
  scale_color_discrete(
    name = "替换为你需要的图例标题",
    labels = c("0对应的自定义说明", "1对应的自定义说明")
  ) +
  # 把theme_bw()放在所有自定义theme配置之前，避免覆盖自定义参数
  theme_bw() + 
  theme(axis.text.x = element_text(angle = 90, vjust=0, hjust=1)) +
  theme(legend.position=c(0.8, 0.1)) +
  theme(plot.title = element_text(hjust = 0.5, size=10))

如果你不想在scale里修改，也可以提前把字段转成自定义标签的因子：

# 提前转换因子并设置标签
a$V_tour_update <- factor(a$V_tour_update, levels = c(0,1), labels = c("0对应的自定义说明", "1对应的自定义说明"))

# 绘图时直接映射，用labs修改图例标题
ggplot(a, aes(x=sold_date_yq, y=average_sold_sqft)) +
  geom_line(aes(color=V_tour_update), size = 1) + 
  scale_x_yearqtr(format="%YQ%q",n=6) + 
  scale_y_continuous(limits = c(300,1200)) +
  labs(color = "替换为你需要的图例标题") +
  theme_bw() + 
  theme(axis.text.x = element_text(angle = 90, vjust=0, hjust=1)) +
  theme(legend.position=c(0.8, 0.1)) +
  theme(plot.title = element_text(hjust = 0.5, size=10))

两种方法都可以实现你的需求，按需选择即可。

内容的提问来源于stack exchange，提问作者Yellow_truffle