R 在使用geom_abline创建的线之间打印功能区

我试图在使用

geom\u abline

require(ggplot2)

val_intcpt <- c(-1,1)

ggplot() + 
  geom_point(data = iris, mapping = aes(x = Petal.Length, y = Sepal.Width)) +
  geom_abline(intercept = 0, slope = 1, linetype = 'dashed') +
  geom_abline(intercept = val_intcpt, slope = 1, linetype = 'dotted') 

require（ggplot2）
val_intcpt也许可以绘制一个多边形

# let ss be the slope for geom_abline
ss <- 1

p <- ggplot() + 
  geom_point(data = iris, mapping = aes(x = Petal.Length, y = Sepal.Width)) +
  geom_abline(intercept = 0, slope = ss, linetype = 'dashed') +
  geom_abline(intercept = val_intcpt, slope = ss, linetype = 'dotted') 

# get plot limits
p.x <- layer_scales(p)$x$get_limits()
p.y <- layer_scales(p)$y$get_limits()

# create polygon coordinates, setting x positions somewhere
# beyond the current plot limits
df <- data.frame(
  x = rep(c(p.x[1] - (p.x[2] - p.x[1]),
            p.x[2] + (p.x[2] - p.x[1])), each = 2),
  intcpt = c(val_intcpt, rev(val_intcpt))
) %>%
  mutate(y = intcpt + ss * x)

# add polygon layer, & constrain to previous plot limits
p +
  annotate(geom = "polygon",
           x = df$x,
           y = df$y,
           alpha = 0.2) +
  coord_cartesian(xlim = p.x, ylim = p.y)


注意x轴限制的值（仍为紫色）：


现在我们有了角点的x/y坐标，构建多边形只需将它们连接在一起：

p5 <- p4 +
  annotate(geom = "polygon",
           x = rep(c(p.x[1] - diff(p.x),
                     p.x[2] + diff(p.x)),
                   each = 2),
           y = c(val_intcpt + ss * (p.x[1] - diff(p.x)),
                 rev(val_intcpt) + ss * (p.x[2] + diff(p.x))),
           fill = "yellow", alpha = 0.4)

p5 +
  ggtitle("Step 5: Draw polygon based on calculated coordinates") +
  annotate(geom = "label",
           x = rep(c(p.x[1] - diff(p.x),
                     p.x[2] + diff(p.x)),
                   each = 2),
           y = c(val_intcpt + ss * (p.x[1] - diff(p.x)),
                 rev(val_intcpt) + ss * (p.x[2] + diff(p.x))),
           label = c("list(x[0] - (x[1] - x[0]), a[1] + b*(x[0] - (x[1] - x[0])))",
                     "list(x[0] - (x[1] - x[0]), a[2] + b*(x[0] - (x[1] - x[0])))",
                     "list(x[1] + (x[1] - x[0]), a[2] + b*(x[1] + (x[1] - x[0])))",
                     "list(x[1] + (x[1] - x[0]), a[1] + b*(x[1] + (x[1] - x[0])))"),
           parse = TRUE, hjust = rep(c(0, 1), each = 2))


（注意：这里有很多不必要的代码，用于为中间步骤添加标签和颜色，以便于演示。对于实际使用，按照我最初的解决方案，这些都不是必需的。但就解释而言，要么是这个，要么是我蹩脚的笔迹中的草图+扫描…）
是的，这是一个很好的破解：）我不知道
图层缩放
。再一次，我从你身上学到了很多：）我会等一小会儿再接受答案，不过，可能还有其他建议。解决方案对我的示例（以及我的要求）很好，但不适用于不同的坡度。你是建议编辑这个问题，使之更一般，还是提出一个新问题？很高兴两者都做（对不起，我觉得很愚蠢）。我承认我根本不理解你的解决方案为什么有效。为什么使用绘图限制的坐标会产生正确的多边形？？那超出了我的想象ken@Tjebo我刚看到你的问题&现在我感觉很糟糕将更新我的答案以合并不同的坡度。哇！！非常感谢。需要在周末花一点时间一步一步地了解它：）
p.x <- layer_scales(p)$x$get_limits()
p.y <- layer_scales(p)$y$get_limits()

p1 <- p + 
  geom_point(data = data.frame(x = p.x, y = p.y) %>% tidyr::complete(x, y),
             aes(x = x, y = y), 
             size = 2, stroke = 1, color = "purple")

p1 + ggtitle("Step 1: Get plot limits")

p2 <- p1 +
  annotate(geom = "text", x = p.x, y = min(p.y), label = c("x[0]", "x[1]"), 
           vjust = -1, parse = TRUE, color = "purple", size = 4)

p2 + 
  ggtitle("Step 2: Note x-axis coordinates of limits") +
  annotate(geom = "segment", 
           x = p.x[1] + diff(p.x), 
           xend = p.x[2] - diff(p.x), 
           y = min(p.y), yend = min(p.y),
           color = "purple", linetype = "dashed", size = 1,
           arrow = arrow(ends = "both")) +
  annotate(geom = "text", x = mean(p.x), y = min(p.y), label = "x[1] - x[0]",
           vjust = -1, parse = TRUE, color = "purple", size = 4)

p3 <- p2 +
  annotate(geom = "point", 
           x = c(p.x[1] - diff(p.x), p.x[2] + diff(p.x)), y = min(p.y),
           shape = 4, size = 1, stroke = 2) +
  annotate(geom = "text", 
           x = c(p.x[1] - diff(p.x), p.x[2] + diff(p.x)), y = min(p.y),
           label = c("x[0] - (x[1] - x[0])", "x[1] + (x[1] - x[0])"),
           vjust = -1, parse = TRUE, size = 5, hjust = c(0, 1))

p3 +
  ggtitle("Calculate x-axis coordinates of two points far beyond the limits") +
  annotate(geom = "segment", 
           x = p.x, 
           xend = p.x + c(-diff(p.x), diff(p.x)), 
           y = min(p.y), yend = min(p.y),
           linetype = "dashed", size = 0.5,
           arrow = arrow(ends = "both", length = unit(0.1, "inches"))) 

p4 <- p3 + 
  annotate(geom = "point",
           x = c(p.x[1] - diff(p.x), p.x[2] + diff(p.x)),
           y = val_intcpt[2] + ss * c(p.x[1] - diff(p.x), p.x[2] + diff(p.x)),
           shape = 8, size = 2, stroke = 2, col = "red") + 
  annotate(geom = "point",
           x = c(p.x[1] - diff(p.x), p.x[2] + diff(p.x)),
           y = val_intcpt[1] + ss * c(p.x[1] - diff(p.x), p.x[2] + diff(p.x)),
           shape = 8, size = 2, stroke = 2, col = "blue")

p4 +
  ggtitle("Calculate the corresponding y coordinates for both ab-lines") +
  annotate(geom = "text",
           x = p.x[1] - diff(p.x),
           y = val_intcpt + ss * (p.x[1] - diff(p.x)),
           label = c("y == a[1] + b * (x[0] - (x[1] - x[0]))", 
                     "y == a[2] + b * (x[0] - (x[1] - x[0]))"), 
           hjust = -0.2, parse = TRUE, 
           color = c("blue", "red")) +
  annotate(geom = "text",
           x = p.x[2] + diff(p.x),
           y = val_intcpt + ss * (p.x[2] + diff(p.x)),
           label = c("y == a[1] + b * (x[1] + (x[1] - x[0]))", 
                     "y == a[2] + b * (x[1] + (x[1] - x[0]))"), 
           hjust = 1.2, parse = TRUE, 
           color = c("blue", "red"))

p5 <- p4 +
  annotate(geom = "polygon",
           x = rep(c(p.x[1] - diff(p.x),
                     p.x[2] + diff(p.x)),
                   each = 2),
           y = c(val_intcpt + ss * (p.x[1] - diff(p.x)),
                 rev(val_intcpt) + ss * (p.x[2] + diff(p.x))),
           fill = "yellow", alpha = 0.4)

p5 +
  ggtitle("Step 5: Draw polygon based on calculated coordinates") +
  annotate(geom = "label",
           x = rep(c(p.x[1] - diff(p.x),
                     p.x[2] + diff(p.x)),
                   each = 2),
           y = c(val_intcpt + ss * (p.x[1] - diff(p.x)),
                 rev(val_intcpt) + ss * (p.x[2] + diff(p.x))),
           label = c("list(x[0] - (x[1] - x[0]), a[1] + b*(x[0] - (x[1] - x[0])))",
                     "list(x[0] - (x[1] - x[0]), a[2] + b*(x[0] - (x[1] - x[0])))",
                     "list(x[1] + (x[1] - x[0]), a[2] + b*(x[1] + (x[1] - x[0])))",
                     "list(x[1] + (x[1] - x[0]), a[1] + b*(x[1] + (x[1] - x[0])))"),
           parse = TRUE, hjust = rep(c(0, 1), each = 2))

p5 +
  ggtitle("Step 6: Reset plot range to original range") +
  coord_fixed(ratio = 1.5, xlim = p.x, ylim = p.y)