Question

目标

我正在尝试用R中的ggplot生成的图中的两条线之间填充区域。我想用不同于水平线下方的颜色填充水平线上方的线之间的所有内容。

我成功用一种颜色填充了两行之间的所有内容，但是，我没有设法用两种不同的颜色来区分垂直线上方和下方。

代码

set.seed(123) 

# Load packages
library(tidyverse)

# Create sample dataframe
df <- data.frame(x=seq(1,50,1),y=runif(50, min = 0, max = 10))

# Generate plot
ggplot(data = df, aes(x = x, y = y)) +
  geom_line() +
  geom_hline(yintercept = 5) +
  theme_classic() +
  geom_ribbon(aes(ymin=5,ymax=y), fill="blue")

问题

如何用不同的颜色填充垂直线上方和下方的空间？

Answer 1

您可以计算两条线相交的点的坐标并将其添加到数据框中：

m <- 5 # replace with desired y-intercept value for the horizontal line

# identify each run of points completely above (or below) the horizontal
# line as a new section
df.new <- df %>%
  arrange(x) %>%
  mutate(above.m = y >= m) %>%
  mutate(changed = is.na(lag(above.m)) | lag(above.m) != above.m) %>%
  mutate(section.id = cumsum(changed)) %>%
  select(-above.m, -changed)

# calculate the x-coordinate of the midpoint between adjacent sections
# (the y-coordinate would be m), & add this to the data frame
df.new <- rbind(
  df.new,
  df.new %>%
    group_by(section.id) %>%
    filter(x %in% c(min(x), max(x))) %>%
    ungroup() %>%
    mutate(mid.x = ifelse(section.id == 1 | 
                            section.id == lag(section.id), 
                          NA,
                          x - (x - lag(x)) / 
                            (y - lag(y)) * (y - m))) %>% 
    select(mid.x, y, section.id) %>%
    rename(x = mid.x) %>%
    mutate(y = m) %>%
    na.omit())

有了这个数据框，您就可以定义两个单独的geom_ribbon层，它们具有不同的颜色。下面的结果比较（注意：我还添加了一个geom_point层用于说明，并更改了颜色，因为原始的蓝色在眼睛上有点刺眼...）

p1 <- ggplot(df,
             aes(x = x, y = y)) +
  geom_ribbon(aes(ymin=5, ymax=y), fill="dodgerblue") +
  geom_line() +
  geom_hline(yintercept = m) +
  geom_point() + 
  theme_classic()

p2 <- ggplot(df.new, aes(x = x, y = y)) +      
  geom_ribbon(data = . %>% filter(y >= m),
              aes(ymin = m, ymax = y), 
              fill="dodgerblue") +
  geom_ribbon(data = . %>% filter(y <= m),
              aes(ymin = y, ymax = m), 
              fill = "firebrick1") +
  geom_line() +
  geom_hline(yintercept = 5) +
  geom_point() +      
  theme_classic()

Answer 2

创建一个新的玩具变量z。如果5等于y>5，则取值y。

df <- df %>% 
  mutate(z = ifelse(y>5, y, 5))

然后使用geom_ribbon()添加第二层z。

生成图：

ggplot(data = df, aes(x = x, y = y)) +
  geom_line() +
  geom_ribbon(aes(ymin=5,ymax=y), fill="red", color="red")+
  geom_ribbon(aes(ymin=5, ymax=z), fill="blue", color="blue") +
  geom_hline(yintercept = 5) + # move this under geom_ribbon for a nicer result
  theme_minimal()

但是，这并不是Z.Lin所注意的，因为蓝色部分延伸到了直线上。我认为这个问题无法解决。

数据：

library(ggplot2)
library(dplyr)
df <- data.frame(x=seq(1,50,1),y=runif(50, min = 0, max = 10))

Answer 3

依次填充三层，以获得非常丑陋的结果：

# Generate plot
ggplot(data = df, aes(x = x, y = y)) +
  geom_line() +
  geom_hline(yintercept = 5) +
  theme_classic() +
  geom_ribbon(aes(ymin=y,ymax=10), fill="green")+
  geom_ribbon(aes(ymin=0,ymax=y), fill="yellow")+
  geom_ribbon(aes(ymin=5,ymax=y), fill="blue")

在R中使用ggplot填充线之间的区域

3 个答案: