根據線型向ggplot折線圖添加圖例

Question

我正在嘗試將圖例添加到使用實線和虛線的 ggplot 圖中。

require(ggplot2)

DATE <- c("2020-10-14", "2020-10-15", "2020-10-16", "2020-10-17", "2020-10-18")
TMAX <- c(47, 45, 43, 40, 4)
TMIN <- c(35, 34, 28, 26, 29)

df <- data.frame(DATE, TMAX, TMIN)

ggplot(data = df, aes(x = DATE, y = TMIN, group = 1)) +
  geom_path(linetype = 1, size = 1.5) +
  labs(x = "Date",
       y = "Temp (F)") +
  theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1)) + 
  geom_path(data = df, linetype = 2, size = 1.5, aes(x = DATE, y=TMAX)) 

一個類似的問題指出我應該在aes中包含linetype ，盡管這不會產生圖例。 例如：

ggplot(data = df, aes(x = DATE, y = TMIN, group = 1, linetype = 1)) +
  geom_path(size = 1.5) +
  labs(x = "Date",
       y = "Temp (F)") +
  theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1)) + 
  geom_path(data = df, size = 1.5, aes(x = DATE, y=TMAX, linetype=2)) 

這是錯誤：

Error: A continuous variable can not be mapped to linetype

如何向顯示我的實線和虛線的圖形添加圖例？

Answer 1

嘗試將此數據整形為 long，然后在 linetype 語句中使用變量。 這樣就可以獲得傳說了。 這里的代碼：

require(ggplot2)
require(tidyr)
require(dplyr)
#Data
DATE <- c("2020-10-14", "2020-10-15", "2020-10-16", "2020-10-17", "2020-10-18")
TMAX <- c(47, 45, 43, 40, 4)
TMIN <- c(35, 34, 28, 26, 29)
df <- data.frame(DATE, TMAX, TMIN)
#Plot
df %>% pivot_longer(-DATE) %>%
  ggplot(aes(x = DATE, y = value, group = name,linetype=name)) +
  geom_path(size = 1.5) +
  labs(x = "Date",
       y = "Temp (F)") +
  theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1))+
  scale_linetype_manual(values=c(2,1))+labs(linetype='Var')+
  guides(linetype = guide_legend(override.aes = list(size = 0.5)))

Output：

Answer 2

如果您只有兩行，則重塑的替代方法是將線型作為字符分配放在aes中

ggplot(data = df, aes(x = DATE, y = TMIN, group = 1)) +
  geom_path(aes(linetype = "TMIN"), size = 1.5) +
  geom_path(aes(y = TMAX, linetype = "TMAX"), size = 1.5) +
  labs(x = "Date", y = "Temp (F)") +
  theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust = 1))