如何使用ggplot在同一圖中繪制兩條平滑樣條線？

Question

例如，我有幾個這樣的情節：

ggplot(mpg, aes(displ, hwy)) +
geom_point() +
geom_smooth(method = "lm", formula = y ~ splines::bs(x, 3), se = T)

是否可以將此類2繪制到同一圖中？

Answer 1

如果只想添加其他功能，請添加另一層： + geom_smooth()

ggplot(mpg, aes(displ, hwy)) + geom_point() + 
geom_smooth(method = "lm", formula = y ~ splines::bs(x, 3), se = T) +
geom_smooth(method = "lm", formula = y ~ splines::bs(x, 4), se = T)

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如果要添加其他數據框中的數據，請在geom_smooth內添加df信息：

ggplot(mpg, aes(displ, hwy)) + geom_point() + 
geom_smooth(method = "lm", formula = y ~ splines::bs(x, 3), se = T) + 
geom_smooth(data = mpg, aes(x = displ, y = cyl), method = "lm", formula = y ~ splines::bs(x, 4), se = T)

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最后，自定義顏色和圖例： color參數必須位於aes內部才能出現在圖例中

ggplot(mpg, aes(displ, hwy)) + geom_point() + 
geom_smooth(aes(color = "B"),method = "lm", formula = y ~ splines::bs(x, 3), se = T) + 
geom_smooth(data = mpg, aes(x = displ, y = cyl, color = "A"), method = "lm", formula = y ~ splines::bs(x, 4), se = T) + 
scale_color_manual("Legend Title", values = c("A" = "red", "B" = "blue"))