积聚控制节点的位置

Question

在冲积图中，我想控制节点的垂直位置。具体来说，我想对齐相同值的节点（例如，秋季为“ Meet”，春季为“ Meet”），以避免像下面的蓝色示例（倾斜表示错误增长）中的蓝色倾斜坡地一样。如果我可以将相同值的节点在相同的y轴值上居中，我想我可以将这种错误信号降到最低。

library(ggalluvial)
library(tidyverse)

set.seed(57)

levels_score <- c("Below", "Meet")

ds_sankey <- 
  tibble(
    fall = c("Below", "Below", "Meet", "Meet"),
    spring = c("Below", "Meet", "Below", "Meet"),
    n = runif(n = 4, min = 100, max = 500)
  ) %>% 
  mutate(
    fall = factor(fall, levels = levels_score),
    spring = factor(spring, levels = levels_score),
    n = round(n)
  ) 

ds_sankey %>% 
  ggplot(aes(y = n, axis1 = fct_rev(fall), axis2 = fct_rev(spring))) +
  geom_alluvium(width = 1/12) +
  geom_stratum(width = 1/4, color = "grey") +
  geom_label(stat = "stratum", label.strata = TRUE) +
  scale_x_discrete(limits = c("fall", "spring"), expand = c(.05, .05))