ggalluvial图：流量百分比取整与标签位置调整需求

问题说明 #

在绘制ggalluvial图并添加流量百分比时，遇到两个核心问题：

• 百分比的小数位数无固定规则，随空间自动调整，需要实现固定取整效果（如整数或指定小数位数）
• 百分比标签与ggrepel生成的地层标注线重叠，需要微调标签的x轴位置规避冲突

数据准备 #

allu5 = data.frame(mult_conc2 = as.factor(c("mtx", "mtx", "none", "mtx", "multi", "mtx", "none", "multi")), 
                   cond_psoriasis = as.factor(c(0, 1, 1, 1, 0, 0, 1, 1)), 
                   bio_drug_name = as.factor(c("rituximab", "anakinra", "rituximab", "baricitinib", 
                                               "etanercept", "etanercept", "ustekinumab", "guselkumab")), 
                   count =  c(50, 50, 40, 70, 30, 25, 25, 70))
 
colorfill = c("tomato4", "tomato3", "tomato2", "tomato1", "tomato", "turquoise", 
              "yellow2", "steelblue1", "springgreen", "snow3", "slategray2", "red1", "purple", "plum1", 
              "olivedrab2")

修改后的完整代码 #

library(ggplot2)
library(ggalluvial)

ggplot(allu5, aes(y = count, axis1 = bio_drug_name, axis2 = mult_conc2)) +
  geom_alluvium(aes(fill = bio_drug_name), width = 1 / 12) +
  geom_stratum(alpha = 1, width = 1 / 5, fill = "#ffffff", color = "black") +
  
  ggrepel::geom_label_repel(stat = "stratum", aes(label = after_stat(stratum)), size = 6,
                            direction = "y", nudge_x = .25, label.size = 0) +
  scale_x_discrete(limits = c("bio drug name", "concomitant"), expand = c(0.1, 0.1)) +
  scale_fill_manual(values = colorfill) +
  guides(fill = "none") +
  ggtitle("b-tsDMARD, concommitant treatment and condition") +
  theme(legend.position = "none") +
  # 解决两个问题的核心改动
  geom_text(stat = "flow", 
            aes(label = scales::percent(after_stat(count)/after_stat(max(ymax)), accuracy = 1),
                hjust = after_stat(flow) == "to"),
            nudge_x = ifelse(after_stat(flow) == "to", 0.1, -0.1))

关键改动解释 #

1. 固定百分比小数位
   在scales::percent()函数中添加accuracy参数：

   • accuracy = 1：强制显示整数百分比
   • accuracy = 0.1：保留1位小数，以此类推
     彻底解决小数位数随机变化的问题。

2. 避免标签重叠
   通过nudge_x结合after_stat(flow)判断流向，实现差异化偏移：

   • 当流向为"to"（指向右侧地层）时，标签向右偏移0.1
   • 当流向为"from"（指向左侧地层）时，标签向左偏移0.1
     让标签主动远离地层标注线，彻底解决重叠问题。

内容的提问来源于stack exchange，提问作者joejoe9