R语言ggplot绘制多X轴折线图问题咨询，附示例数据与代码

你可以通过两种常用方案实现需求： #

方案1：借助ggh4x包实现嵌套X轴（效果更贴合示例图） #

ggh4x包扩展了ggplot2的坐标轴能力，可以直接生成多层嵌套的X轴标签：

依赖安装 #

install.packages(c("ggplot2", "ggh4x"))

完整绘图代码 #

library(ggplot2)
library(ggh4x)

# 示例数据
df <- data.frame(
  Time = c(" ","Phase 1","Phase 1","Phase 1","Phase 1"," ",
           " ","Phase 2","Phase 2","Phase 2","Phase 2"," "),
  Condition = c("BO", "BO", "BO", "BO","BO","BO", 
                "OB","OB","OB","OB","OB","OB"), 
  Phase = c("Baseline", "T1", "T2", "T1", "T2", "Follow-Up",
            "Baseline", "T1", "T2", "T1", "T2", "Follow-Up"),
  Change = c(0,-2.84, -5.02, -6.81,-7.41,-6.80, 
             0, -3.35,-6.92,-7.05,-6.59,-6.41)
)

# 锁定X轴顺序避免自动排序错乱
df$x_id <- factor(1:nrow(df), levels = 1:nrow(df))

ggplot(df, aes(x = x_id, y = Change, color = Condition, group = Condition)) +
  geom_line(linewidth = 1) +
  geom_point(size = 2) +
  # 配置三层嵌套X轴
  scale_x_discrete(
    labels = df$Phase,
    guide = axis_nested(
      nest_levels = ~ interaction(Phase, Condition, Time),
      expand = c(0,0.5)
    )
  ) +
  labs(x = NULL, y = "Change") +
  theme_bw() +
  theme(
    axis.text.x = element_text(angle = 45, hjust = 1),
    ggh4x.axis.nesttext.x = element_text(hjust = 0.5),
    ggh4x.axis.nestline.x = element_line(linewidth = 0.5)
  )

方案2：ggplot2原生分面实现（无需额外依赖） #

用分面功能将分组标签放在X轴外侧充当多层标签，适配性更强：

library(ggplot2)

# 复用上述df数据
ggplot(df, aes(x = Phase, y = Change, color = Condition, group = Condition)) +
  geom_line(linewidth = 1) +
  geom_point(size = 2) +
  # 分面充当外层X轴标签
  facet_grid(~ Condition + Time, scales = "free_x", space = "free_x", switch = "x") +
  labs(x = NULL, y = "Change") +
  theme_bw() +
  theme(
    axis.text.x = element_text(angle = 45, hjust = 1),
    strip.placement = "outside",
    strip.background.x = element_blank()
  )

两种方案都可以实现多X轴效果，你可以根据自己的需求调整线条样式、颜色、字号等主题参数。

内容的提问来源于stack exchange，提问作者Matt Landry