平面冲积图中可变对齐ggrepel文本标签

Question

我试图创建一个多面冲积图，在第一轴上的图层贴上标签，左和左对齐，右边的标签被右和右对齐。

# Small working example

# Install Packages and Libraries
install.packages("ggplot2")
install.packages("ggalluvial")
install.packages("ggrepel")
library(ggplot2)
library(ggalluvial)
library(ggrepel)

# Data Frame with 2 regions, 3 supply sectors and 3 demand sectors
df <- data.frame(region = c("A","A","A","B","B","B"),
                 supplySector = c("coal","gas","wind","coal","gas","wind"),
                 demandSector = c("resid","indus","ag","resid","indus","ag"),
                 value = 10*runif(6)); df    

# Faceted plot with ggrepel (nudge_x and hjust assigned for each label) works.
p <- ggplot(df, aes(y = value, axis1 = supplySector, axis2 = demandSector, group=region)) +
  ggalluvial::geom_alluvium(aes(fill = supplySector), width = 1/12, color="black", alpha=0.6) +
  ggalluvial::geom_stratum(width = 1/12, fill = "grey70", color = "grey10", alpha=1) +
  scale_x_discrete(limits = c("supplySector", "demandSector"), expand = c(0.3,0),drop=F) +
  facet_wrap(region~.) +
  ggrepel::geom_text_repel(stat = "stratum", label.strata = TRUE, direction = "y", 
                           size = 4, segment.color = 'grey50', 
                           nudge_x = rep(c(-3,-3,-3,3,3,3),2),
                           hjust = rep(c(1,1,1,-1,-1,-1),2)); p

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# Faceted plot with ggrepel (nudge_x and hjust assigned for each label)
# does not work when different number of variables in each facet

df1 <- df[-nrow(df),]; df1  # Remove one of the rows from df

# So this gives the following plot with different alluvia in each facet
p1 <- ggplot(df1, aes(y = value, axis1 = supplySector, axis2 = demandSector, group=region)) +
  ggalluvial::geom_alluvium(aes(fill = supplySector), width = 1/12, color="black", alpha=0.6) +
  ggalluvial::geom_stratum(width = 1/12, fill = "grey70", color = "grey10", alpha=1) +
  scale_x_discrete(limits = c("supplySector", "demandSector"), expand = c(0.3,0),drop=F) +
  facet_wrap(region~.); p1

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# If we try and label these and assigns the nudge and hjust for each axis we get an error
# It expects the same length vector for nudge and hjust for each facet
p1 + ggrepel::geom_text_repel(stat = "stratum", label.strata = TRUE, direction = "y", 
                              size = 4, segment.color = 'grey50',
                              nudge_x = rep(c(-3,-3,-3,3,3,3),2),
                              hjust=rep(c(1,1,1,-1,-1,-1),2))
# Gives error: Error: Aesthetics must be either length 1 or the same as the data (10): hjust

# If we adjust the vectors for nudge_x and hjust to 10
p1 + ggrepel::geom_text_repel(stat = "stratum", label.strata = TRUE, direction = "y", 
                              size = 4, segment.color = 'grey50',
                              nudge_x = c(-3,-3,-3,3,3,3,-3-3,3,3),
                              hjust = c(1,1,1,-1,-1,-1,1,1,-1,-1))

# Get Error: Error in data.frame(x = data$x + nudge_x, y = data$y + nudge_y) :
#           arguments imply differing number of rows: 9, 6
#           In addition: Warning message:
#           In data$x + nudge_x :
#           longer object length is not a multiple of shorter object length

# It can be plotted without specifying the nudge_x and hjust values
p1 + ggrepel::geom_text_repel(stat = "stratum", label.strata = TRUE, direction = "y", 
                              size = 4, segment.color = 'grey50')

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总之，我想做的是：

• 对于图p1 (在不同的方面有不同数量的典故)
• 标记每个x轴层列
• 让axis1标签排挤到左边，左对齐
• 让axis2标签向右排斥并正确证明正确

这个答案表明标签的向量长度不同，但对于不同的方面不起作用。Labelling and theme of ggalluvial plot in R

Answer 1

这太棘手了！nudge_*和*just参数通常不是动态的。解决这一问题的一种方法是使用ggplot_build()深入研究内脏。

ggplot_build()掌握了ggplot()如何构建图表的所有“说明”。您可以编辑数据，然后运行plot(ggplot_gtable())来查看修改后的情节。我增加了一些评论，以帮助解释这些步骤。

# here is the base plot + the new layer for labels
plot_and_label <-
  p1 +
  geom_text_repel(
    stat = "stratum", label.strata = TRUE,
    direction = "y", size = 4,
    segment.color = 'grey50',
    nudge_x = 0
  )

# this is the plot under the hood
gg_guts <- ggplot_build(plot_and_label)

# the geom_text_repel layer was the 3rd one we added so you can 
# access and edit it like this
gg_guts$data[[3]] <-   
  gg_guts$data[[3]] %>%
  mutate(hjust = ifelse(x%%2 == 1, 2, -2))

# once you've made your adjustments, you can plot it again
plot(ggplot_gtable(gg_guts))

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