曲线截距作为 y 轴上的文本：ggplot2

Question

我试图将模型的截距值放在 y 轴上。 我使用的代码是这样的：

library(ggplot2)

mod <- lm(circumference ~ age + I(age^2), Orange); summary(mod)
novo_dados <- data.frame(age = seq(0, max(Orange$age), length.out = 100))
valores_previstos <- predict(mod, newdata = novo_dados)
intercepto <- coef(mod)[1]

ggplot(data = Orange, aes(x = age, y = circumference)) +
  geom_point(color = "black", shape = 19, size = 2) +
  coord_cartesian(xlim = c(0,1600), ylim = c(0,250)) +
  geom_line(data = novo_dados, aes(x = age, y = valores_previstos), 
            color = "black", linewidth = 2) +
  labs(title = "Quadratic Model",
       x = "Age",
       y = "Circumference") +
  scale_y_continuous(breaks = c(0, intercepto, max(Orange$circumference)), 
                     labels = c("0", round(intercepto, 2), max(Orange$circumference))) +
  scale_y_continuous(breaks = c(0, 100, 200, 250), labels = c("0", "100", "200", "250")) +
  theme(legend.position = "none",
        axis.title = element_text(size = 30),
        axis.text.x = element_text(color = "black", hjust=1),
        axis.text.y = element_text(color = "black", hjust=1),
        axis.text = element_text(size = 30),
        plot.title = element_text(size = 15),
        strip.text.x = element_text(size = 12))

上面代码的结果是：

但请注意，它随着与将 y 轴上的截距值作为文本包含在内相关的信息而消失，即：

 scale_y_continuous(breaks = c(0, intercepto, max(Orange$circumference)), 
                     labels = c("0", round(intercepto, 2), max(Orange$circumference))) 

当我仅考虑上述部分来运行图表时，我得到了我想要的，但是 y 轴仅显示 y 变量的最大值。

ggplot(data = Orange, aes(x = age, y = circumference)) +
  geom_point(color = "black", shape = 19, size = 2) +
  coord_cartesian(xlim = c(0,1600), ylim = c(0,250)) +
  geom_line(data = novo_dados, aes(x = age, y = valores_previstos), 
            color = "black", linewidth = 2) +
  labs(title = "Quadratic Model",
       x = "Age",
       y = "Circumference") +
  scale_y_continuous(breaks = c(0, intercepto, max(Orange$circumference)), 
                     labels = c("0", round(intercepto, 2), max(Orange$circumference))) +
#  scale_y_continuous(breaks = c(0, 100, 200, 250), labels = c("0", "100", "200", "250")) +
  theme(legend.position = "none",
        axis.title = element_text(size = 30),
        axis.text.x = element_text(color = "black", hjust=1),
        axis.text.y = element_text(color = "black", hjust=1),
        axis.text = element_text(size = 30),
        plot.title = element_text(size = 15),
        strip.text.x = element_text(size = 12))

我希望截距值出现在 y 轴上，但其他 y 轴值没有变化，即保持正常。

Answer 1

拥有两个 y 比例确实只会将指定的最后一个应用于绘图：

Scale for y is already present.
Adding another scale for y, which will replace the existing scale.

但是您可以将截距值和 y 轴值包含在相同的比例中：

head(Orange)
library(ggplot2)

mod <- lm(circumference ~ age + I(age^2), Orange)
novo_dados <- data.frame(age = seq(0, max(Orange$age), length.out = 100))
valores_previstos <- predict(mod, newdata = novo_dados)
intercepto <- coef(mod)[1]

ggplot(data = Orange, aes(x = age, y = circumference)) +
  geom_point(color = "black", shape = 19, size = 2) +
  coord_cartesian(xlim = c(0, 1600), ylim = c(0, 250)) +
  geom_line(data = novo_dados, aes(x = age, y = valores_previstos), 
            color = "black", linewidth = 2) +
  labs(title = "Quadratic Model",
       x = "Age",
       y = "Circumference") +
  scale_y_continuous(breaks = c(0, intercepto, 100, 200, 250), 
                     labels = c("0", round(intercepto, 2), "100", "200", "250")) +
  theme(legend.position = "none",
        axis.title = element_text(size = 30),
        axis.text.x = element_text(color = "black", hjust = 1),
        axis.text.y = element_text(color = "black", hjust = 1),
        axis.text = element_text(size = 30),
        plot.title = element_text(size = 15),
        strip.text.x = element_text(size = 12))

Answer 2

您想要 y 轴刻度上的截距值吗？您只需要调整 y 轴，但不删除您想要的原始断点，如下所示：

head(Orange)
library(ggplot2)

mod <- lm(circumference ~ age + I(age^2), Orange); summary(mod)
novo_dados <- data.frame(age = seq(0, max(Orange$age), length.out = 100))
valores_previstos <- predict(mod, newdata = novo_dados)
intercepto <- coef(mod)[1]

ggplot(data = Orange, aes(x = age, y = circumference)) +
  geom_point(color = "black", shape = 19, size = 2) +
  coord_cartesian(xlim = c(0,1600), ylim = c(0,250)) +
  geom_line(data = novo_dados, aes(x = age, y = valores_previstos), 
            color = "black", linewidth = 2) +
  labs(title = "Quadratic Model",
       x = "Age",
       y = "Circumference") +
  scale_y_continuous(breaks = c(0, intercepto, max(Orange$circumference), 100, 200, 250), ## Include the original breaks
                     labels = c("0", round(intercepto, 2), max(Orange$circumference), "100", "200", "250")) +
  theme(legend.position = "none",
        axis.title = element_text(size = 20), ## Adjust text size for clarity
        axis.text.x = element_text(color = "black", hjust=1),
        axis.text.y = element_text(color = "black", hjust=1),
        axis.text = element_text(size = 15), ## Adjust text size for clarity
        plot.title = element_text(size = 15),
        strip.text.x = element_text(size = 12))