ggarrange输出异常求助：图例重叠模糊、Y轴标签致对齐问题

使用ggarrange将6幅图排列为2列3行布局，设置了共用图例与共用Y轴标题。此前代码可正常生成预期输出，但重新绘图后出现两个问题：

• 图例因两组元素重叠变得模糊不清
• 原共用Y轴标签的实现方案（仅保留第三幅图的Y轴标签）导致左列Y轴对齐混乱

1. 修复图例重叠问题 #

问题根源：每幅图都自带图例，ggarrange的common.legend=TRUE虽会提取共用图例，但原图表的图例并未被移除，导致底层图例和新添加的共用图例重叠。

解决方式：在所有子图中统一移除图例，仅让ggarrange生成共用图例。可通过自定义主题设置legend.position="none"实现。

2. 修复Y轴对齐与共用Y轴标签问题 #

原方案仅保留第三幅图的Y轴标签，导致左列上下图的Y轴宽度不一致，出现对齐偏移。正确做法：

• 移除所有子图的Y轴标签
• 使用annotate_figure的left参数统一添加左侧共用Y轴标签，精准控制位置与样式

require(tidyverse)
require(grid)
require(ggpubr)
require(extrafont)
loadfonts(device = "win")

# 构造数据
list(type = rep(c("(1)", "(2)", "(3)", "(4)","(5)", "(6)"), each = 16), 
     group = rep(rep(c("First Group", "Second Group"), each = 8), 6),  
     x = rep(c(-7, -5, -3, -1, 1, 3, 5, 7), times = 12),
     scale_x = c(0.087, 0.085, 0.083, 0.081, 0.079, 0.077, 0.075, 0.073, 
                 0.087, 0.085, 0.083, 0.081, 0.079, 0.077, 0.075, 0.073, 
                 -7, -5, -3, -1, 1, 3, 5, 7, 
                 -7, -5, -3, -1, 1, 3, 5, 7, 
                 2.2, 2, 1.8, 1.6, 1.4, 1.2, 1, 0.8, 
                 2.2, 2, 1.8, 1.6, 1.4, 1.2, 1, 0.8, 
                 77, 75, 73, 71, 69, 67, 65, 63,
                 77, 75, 73, 71, 69, 67, 65, 63, 
                 -7, -5, -3, -1, 1, 3, 5, 7, 
                 -7, -5, -3, -1, 1, 3, 5, 7, 
                 8.49, 8.51, 8.53, 8.55, 8.57, 8.59, 8.61, 8.63, 
                 8.49, 8.51, 8.53, 8.55, 8.57, 8.59, 8.61, 8.63), 
     y = rep(c(rep(c(-0.7), times = 4), rep(c(0.7), times = 4),
                 rep(c(-0.77), times = 4), rep(c(0.77), times = 4)),
              times = 6)) %>% as_tibble() -> df

# 绘图函数
function_graph <- function(data){   
  data %>%
    ggplot(aes(x = x, y = y, col = group)) +
    geom_line(aes(group = interaction(group))) +
    geom_point(position = position_dodge(width = .2)) + 
    geom_vline(xintercept = 0, linetype = 2) +
    theme_minimal() +
    scale_color_manual(values = c("red", "black")) +
    scale_y_continuous(breaks = seq(-1, 1, length.out = 6)) +
    coord_cartesian(ylim = c(-1, 1), xlim = c(7, -7)) +
    geom_text(aes(label = "left"), 
               y = .95, x = 3.5, size = 3, col = "gray36", family = "Palatino Linotype") +
    geom_text(aes(label = "right"), 
               y = .95, x = -3.5, size = 3, col = "gray36", family = "Palatino Linotype")
}

# 生成6幅子图
df %>% filter(grepl("(1)", type)) %>% 
  pull(scale_x) %>% distinct() %>% arrange() -> x_labels
p_1 <- df %>% filter(grepl("(1)", type)) %>% function_graph() +
  labs(x = "Unit for graph (1)") +
  scale_x_continuous(breaks = rev(seq(-7, 7, length.out = 8)), labels = x_labels)

df %>% filter(grepl("(2)", type)) %>% 
  pull(scale_x) %>% distinct() %>% arrange() -> x_labels
p_2 <- df %>% filter(grepl("(2)", type)) %>% function_graph() +
  labs(x = "Unit for graph (2)") +
  scale_x_continuous(breaks = rev(seq(-7, 7, length.out = 8)), labels = x_labels)

df %>% filter(grepl("(3)", type)) %>% 
  pull(scale_x) %>% distinct() %>% arrange() -> x_labels
p_3 <- df %>% filter(grepl("(3)", type)) %>% function_graph() +
  labs(x = "Unit for graph (3)") +
  scale_x_continuous(breaks = rev(seq(-7, 7, length.out = 8)), labels = x_labels)

df %>% filter(grepl("(4)", type)) %>% 
  pull(scale_x) %>% distinct() %>% arrange() -> x_labels
p_4 <- df %>% filter(grepl("(4)", type)) %>% function_graph() +
  labs(x = "Unit for graph (4)") +
  scale_x_continuous(breaks = rev(seq(-7, 7, length.out = 8)), labels = x_labels)

df %>% filter(grepl("(5)", type)) %>% 
  pull(scale_x) %>% distinct() %>% arrange() -> x_labels
p_5 <- df %>% filter(grepl("(5)", type)) %>% function_graph() +
  labs(x = "Unit for graph (5)") +
  scale_x_continuous(breaks = rev(seq(-7, 7, length.out = 8)), labels = x_labels)

df %>% filter(grepl("(6)", type)) %>% 
  pull(scale_x) %>% distinct() %>% arrange() -> x_labels
p_6 <- df %>% filter(grepl("(6)", type)) %>% function_graph() +
  labs(x = "Unit for graph (6)") +
  scale_x_continuous(breaks = rev(seq(-7, 7, length.out = 8)), labels = x_labels)

# 自定义主题：移除子图图例
theme_own <- function(){
  theme_minimal() %+replace%  
    theme( plot.caption = element_text(color="black", size = 11, hjust = 1),
           axis.title = element_text(size = 9),
           axis.text = element_text(size = 7),
           plot.title=element_text(hjust=0.5, face="bold", size=13, vjust = 2),
           text = element_text(family = "Palatino Linotype"),
           legend.position="none",  # 关键：子图不显示图例
           legend.title = element_blank()
    )
}

# 组合图表并添加标题和共用Y轴
ggarrange(p_1 + theme_own(), 
          p_2 + theme_own(), 
          p_3 + theme_own(), 
          p_4 + theme_own(),
          p_5 + theme_own(),
          p_6 + theme_own(),
          ncol=2, nrow=3, common.legend = TRUE, legend="bottom") %>%
  annotate_figure( 
    top = text_grob("A nice title", color = "black", face = "bold", size = 14, family = "Palatino Linotype"),
    left = text_grob("Common y-axis label", rot = 90, size = 9, family = "Palatino Linotype")  # 添加共用Y轴标签
  )

内容的提问来源于stack exchange，提问作者Luise