ggplot2绘图求助：调整Y轴标签间距与文本居中

问题1：缩小Y轴类别间距 #

将Y轴从连续型转为离散型，移除上下空白区域，同时缩小误差线高度，让元素更紧凑：

• 把aes中的y = ID改为y = factor(ID)，适配类别型数据
• 在scale_y_discrete中添加expand = c(0, 0)，消除Y轴上下的空白
• 调小geom_errorbarh的height参数，减少误差线的纵向占用

问题2：多行标签居中对齐 #

使用ggtext包支持markdown/HTML格式的文本渲染，实现多行标签居中：

• 用<br>替换换行符，并用<center>包裹标签内容
• 在theme中设置axis.text.y = element_markdown(hjust = 0.5)，确保文本居中

完整代码示例 #

# 安装并加载所需包（首次使用需安装ggtext）
install.packages("ggtext")
library(ggplot2)
library(ggtext)

# 你的原始数据
df <- structure(list(vec = c("PC", "DEFAULT", "INFORMED"), mean = c(1.34944359241928, 
                                                          1.36249329506777, 1.34671188869646), sd = c(0.57779881866326, 
                                                                                                      0.537279303541924, 1.53585580464849), min = c(0.196903771571785, 
                                                                                                                                                    0.28781509871908, -1.66860228474139), `0.5quant` = c(1.35295469982876, 
                                                                                                                                                                                                         1.36643973099316, 1.34687516700723), max = c(2.48177705326348, 
                                                                                                                                                                                                                                                      2.41483607230639, 4.36109982194179), mode = c(NA_real_, NA_real_, 
                                                                                                                                                                                                                                                                                                    NA_real_), kld = c(1.9807860333589e-08, 2.97333113261951e-08, 
                                                                                                                                                                                                                                                                                                                       3.91753938449056e-10), ID = 1:3), row.names = c(NA, -3L), class = "data.frame")

# 调整Y轴标签为居中的markdown格式
yaxis <- c(
  "<center>Ppppppppp ppppppp<br>pppp pp pppppp<br>(ppp)</center>",
  "<center>Uuuuuuuuu uuuuu</center>",
  "<center>Iiiiiii iiiii<br>ii Iiiiii (iiii)</center>"
)

# 绘图代码
myplot <- ggplot(data = df, aes(x = mean, y = factor(ID))) +
  geom_point() +
  # 缩小误差线高度，增强紧凑感
  geom_errorbarh(aes(xmin = min, xmax = max), height = 0.05) +
  geom_vline(xintercept = 0, linetype = 2) +
  scale_x_continuous(breaks=seq(-4,4.5,0.5)) +
  # 离散型Y轴，消除上下空白，设置标签
  scale_y_discrete(breaks = 1:3, labels = yaxis, expand = c(0, 0)) +
  # 使用ggtext渲染居中标签
  theme(axis.text.y = element_markdown(hjust = 0.5))

# 显示图形
myplot

无额外包替代方案（手动居中） #

如果不想安装ggtext，可以用stringr::str_pad手动调整每行文本的缩进：

library(stringr)

yaxis <- c(
  paste0(str_pad("Ppppppppp ppppppp", 20, "both"), "\n",
         str_pad("pppp pp pppppp", 20, "both"), "\n",
         str_pad("(ppp)", 20, "both")),
  str_pad("Uuuuuuuuu uuuuu", 20, "both"),
  paste0(str_pad("Iiiiiii iiiii", 20, "both"), "\n",
         str_pad("ii Iiiiii (iiii)", 20, "both"))
)

myplot <- ggplot(data = df, aes(x = mean, y = factor(ID))) +
  geom_point() +
  geom_errorbarh(aes(xmin = min, xmax = max), height = 0.05) +
  geom_vline(xintercept = 0, linetype = 2) +
  scale_x_continuous(breaks=seq(-4,4.5,0.5)) +
  scale_y_discrete(breaks = 1:3, labels = yaxis, expand = c(0, 0)) +
  theme(axis.text.y = element_text(hjust = 0.5))

内容的提问来源于stack exchange，提问作者Rustam