ggplot2/ggarrange图表点标签丢失/重叠问题求助

一、优化标签位置，避免超出与重叠 #

1. 基于数据值动态调整标签位置 #

给数据集添加一列标签位置调整参数，根据数值高低自动设置标签在点的上方或下方，从根源避免标签超出图表范围：

# 为数据添加标签垂直位置调整列
data <- data %>%
  mutate(label_vjust = ifelse(perc*100 > 50, -1.5, 2)) # 数值高于50%时标签在点上方，否则在下方

# 绘图时调用动态调整参数
plot1 <- 
  ggplot(data, aes(x = Year, y = perc*100, colour = Sex)) +
  geom_path(aes(group=Sex)) +
  geom_point() +
  scale_color_manual(values=c("skyblue3", "darkred"))+
  labs(title = "Sex Ratio", x = "years", y = "percentage") +
  theme(plot.title = element_text(hjust = 0.5), panel.grid.major.x = element_blank()) +
  geom_text(aes(label = paste0(round(perc*100), "%"), vjust = label_vjust), 
            position = position_dodge(width =1), size = 2.5, colour = "black", check_overlap = TRUE)

2. 使用ggrepel包自动避让标签 #

ggrepel的geom_text_repel会智能调整标签位置，自动避开重叠和图表边界，比原生geom_text适配性更强：

library(ggrepel)

plot1 <- 
  ggplot(data, aes(x = Year, y = perc*100, colour = Sex)) +
  geom_path(aes(group=Sex)) +
  geom_point() +
  scale_color_manual(values=c("skyblue3", "darkred"))+
  labs(title = "Sex Ratio", x = "years", y = "percentage") +
  theme(plot.title = element_text(hjust = 0.5), panel.grid.major.x = element_blank()) +
  geom_text_repel(aes(label = paste0(round(perc*100), "%")), 
                  position = position_dodge(width =1), size = 2.5, colour = "black",
                  box.padding = 0.3, point.padding = 0.5) # 可调整标签与点的间距

二、单独调整特定标签的位置 #

如果只需修改个别标签的位置，可在数据集中标记目标标签，分两次绘制普通标签和特殊标签：

# 标记需要单独调整的标签（示例：2023年男性的标签）
data <- data %>%
  mutate(is_special = (Year == 2023 & Sex == "Male"))

plot1 <- 
  ggplot(data, aes(x = Year, y = perc*100, colour = Sex)) +
  geom_path(aes(group=Sex)) +
  geom_point() +
  scale_color_manual(values=c("skyblue3", "darkred"))+
  labs(title = "Sex Ratio", x = "years", y = "percentage") +
  theme(plot.title = element_text(hjust = 0.5), panel.grid.major.x = element_blank()) +
  # 绘制普通标签
  geom_text(data = filter(data, !is_special),
            aes(label = paste0(round(perc*100), "%")), 
            position = position_dodge(width =1), vjust = 2, size = 2.5, colour = "black", check_overlap = TRUE) +
  # 绘制特殊标签并单独调整位置
  geom_text(data = filter(data, is_special),
            aes(label = paste0(round(perc*100), "%")), 
            position = position_dodge(width =1), vjust = -1, size = 2.5, colour = "black")

三、调整合并图表的边距与尺寸 #

合并时通过ggarrange的参数预留更多空间，或在保存时调整整体尺寸：

plot_together <- ggarrange(plot1, plot2, plot3, ncol = 2, nrow = 2,
                           common.legend = TRUE, legend = "bottom",
                           margins = 0.2, # 增加图表四周边距
                           heights = c(1,1), widths = c(1,1)) # 保证各面板尺寸一致

# 保存时扩大整体画布，给标签足够显示空间
ggsave("plot_together.png", plot_together, width = 12, height = 10, dpi = 300)

内容的提问来源于stack exchange，提问作者Manuel