如何在填充的等高线图中绘制水平线并标记它？

Question

我有以下等高线图

x <- c(0,25,50,75,100)
y <- c(0,10,20)
z <- matrix(c(12,12,13,12,5,12,5,5,5,12,5,12,13,14,15), nrow = 5, ncol = 3, byrow = TRUE)
A <- matrix(seq(0, 100, by = 25), nrow = 3, ncol = 5, byrow = TRUE) #As x
B <- matrix(seq(0,20, by = 10), nrow = 3, ncol = 5) #As y
filled.contour(x,y,z, color=terrain.colors,#
  plot.axes = { axis(1); axis(2); points(A,B)})

如何在值5的水平周围绘制一个水平线并标记它并获得如下内容：

Answer 1

您可以在contour中使用plot.axes。不可能将行添加到5，所以我使用了5.01而是指定了labels。这至少是原则。

filled.contour(x, y, z, color = terrain.colors,
               plot.axes = {axis(1); axis(2); points(A, B);
                 contour(x, y, z, levels = 5.01, labels = "5", col = "red", add = TRUE)})

Answer 2

library(fields)
library(emdbook)

x <- c(0,25,50,75,100)
y <- c(0,10,20)
z <- matrix(c(12,12,13,12,5,12,5,5,5,12,5,12,13,14,15), nrow = 5, ncol = 3, byrow = TRUE)
A <- matrix(seq(0, 100, by = 25), nrow = 3, ncol = 5, byrow = TRUE) #As x
B <- matrix(seq(0,20, by = 10), nrow = 3, ncol = 5) #As y


image.plot(x,y,z)
contour(x,y,z,
    add=TRUE, lwd=2, cex=2)