如何填充ggplot图中两条曲线之间的间隙

Question

我想将一个简单的三次多项式拟合到数据，然后构建具有三种不同几何形状的图形：我在其上拟合模型的一组数据点（蓝色的geom_point，这些点+预测间隔（geom_line，也为蓝色）和对模型适用的天数的预测（geom_line，为红色）。这是我的代码：

library(ggplot2)

positives <- c(13, 65, 118, 229, 322, 455, 655, 888, 1128, 1577)
days_passed <- length(positives)
t <- seq(1, days_passed)
t_full <- c(t, seq(t[days_passed], 30))

model <- lm(positives ~ poly(t,degree=3))

predict_positives <- predict(model, list(t = t_full), interval = "prediction")

# plot
length(positives) <- length(t_full)
dframe <- data.frame(day = t_full, 
                     positives = positives,
                     future = ifelse(t_full <= days_passed, "N", "Y"),
                     lwr = predict_positives[, "lwr"],
                     fit = predict_positives[, "fit"],
                     upr = predict_positives[, "upr"])
p <- ggplot(dframe, aes(x = day, y = positives, color = future)) +
  geom_point() +
  geom_line(aes(y = fit)) +
  geom_line(aes(y = lwr), linetype = "dashed") +
  geom_line(aes(y = upr), linetype = "dashed") +
  geom_vline(xintercept = 17, linetype = "dashed") + 
  geom_vline(xintercept = 24)

print(p)

但是，结果图显示出不美观的间隙：

如何修改我的代码，以使拟合和预测是连续的？

Answer 1

您的future列的第10天对应的两行的值均为N。如果您仅更改此值，则图将显示您的预期。

dframe$future[11] <- "Y"

ggplot(dframe, aes(x = day, y = positives, color = future)) +
  geom_point() +
  geom_line(aes(y = fit)) +
  geom_line(aes(y = lwr), linetype = "dashed") +
  geom_line(aes(y = upr), linetype = "dashed") +
  geom_vline(xintercept = 17, linetype = "dashed") + 
  geom_vline(xintercept = 24)