r - 在 ggplot 中添加趋势线作为附加图例

Question

我有一个散点图，显示随时间变化的连续数据。我的数据由两个变量(类型和级别)来区分，这两个变量在图例中表示。我已向数据添加了趋势线，并希望将其作为单独的图例(除了类型和级别之外)并将其标记为“趋势线”。我将不胜感激任何有关实现这一目标的最有效方法的建议。谢谢!

这是一个可重现的示例:

library(tidyverse)

perc <- c(.5, .49, .67, .5, .67, .73, .82)
year <- c(2000, 2001, 2002, 2003, 2004, 2005, 2006)
type <- c(1, 1, 1, 1, 1, 2, 2)
type <- as.factor(type)
level <- c(3, 3, 3, 4, 4, 4, 4)
level <- as.factor(level)
data <- data.frame(year, perc, type, level)

ggplot(data, aes(x=year, y=perc, color = type, shape = level)) +
  geom_point(size = 3) +
  geom_smooth(aes(group = 1), method = "lm", se = FALSE) +
  scale_color_manual(values = c("red", "black")) +
  scale_shape_manual(values = c(16, 17))

Answer 1

这对我有用:

library(tidyverse)

perc <- c(.5, .49, .67, .5, .67, .73, .82)
year <- c(2000, 2001, 2002, 2003, 2004, 2005, 2006)
type <- c(1, 1, 1, 1, 1, 2, 2)
type <- as.factor(type)
level <- c(3, 3, 3, 4, 4, 4, 4)
level <- as.factor(level)
data <- data.frame(year, perc, type, level)

ggplot(data, aes(x=year, y=perc, color = type, shape = level, linetype = "Trendline")) +
  geom_point(size = 3) +
  geom_smooth(aes(group = 1), method = "lm", se = FALSE) +
  scale_color_manual(values = c("red", "black")) +
  scale_shape_manual(values = c(16, 17)) +
  scale_linetype_discrete(name = "")