图中多条线之间的填充区域

Question

我有一个包含 3 行的图，如下所示：

a = data.frame(time = c(1:100), x = rnorm(100))
b = data.frame(time = c(1:100), y = rnorm(100))
c = data.frame(time = c(1:100), z = rnorm(100))

plot(a$time, a$x, type = 'l')
lines(b$time, b$y, type = 'l')
lines(c$time, c$z, type = 'l')

我需要填充线的最低值和最大值之间的区域，以便获得给定颜色的唯一多边形。

我知道 polygon 函数，但我不知道在这种情况下如何使用它。

有什么建议吗？谢谢

Answer 1

这里有一个方法：

a = data.frame(time = c(1:100), x = rnorm(100))
b = data.frame(time = c(1:100), y = rnorm(100))
c = data.frame(time = c(1:100), z = rnorm(100))

计算 pmin 和 pmax:

min_a <- pmin(a, b, c)
max_a <- pmax(a, b, c)

照常构造多边形：

polygon(c(c$time, rev(c$time)), c(max_a$x ,rev(min_a$x)), col = rgb(1, 0, 0,0.5) )

或使用 ggplot:

library(tidyverse)
data.frame(a, b, c) %>% #combine the three data frames
  group_by(time) %>% # group by time for next step
  mutate(max = max(x, y, z), # calculate max of x, y, z in each time
         min = min(x, y, z)) %>% #same as above
  select(-time.1, - time.2) %>% #discard redundant columns
  gather(key, value, 2:4) %>% #convert to long format so you can color by key in the geom line call
  ggplot()+
  geom_ribbon(aes(x = time, ymin= min, ymax = max), fill= "red", alpha = 0.3)+
  geom_line(aes(x = time, y = value, color = key))

图中多条线之间的填充区域

Fill area between multiple lines in plot

plot

r

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area

fill