GGRidges:单一密度图太高

Question

我有一个数据框架，它由一个因变量和多个自变量组成。一组关系来自不同的测试(但这对于解决我遇到的问题并不重要)。

我使用包ggridges来表示一个图，每个关系都有密度图。当一个关系只有一个值时，ggridges会产生一个点，而不是密度图。我的问题是，在这种情况下，下面的密度图与上面的空间重叠。可能是因为ggridges没有看到另一个密度图，并且扩展了下面的密度图可以占用的空间。选项"scale“可以用来避免两个密度图的重叠，但不能避免密度图和一个点之间的重叠(至少我这么认为)。

如果我设置scale = 0.5，我可以解决这个问题，但这不是最好的做法，因为每个密度图都会变小。也包括那些不与其他对象重叠的对象。

下面我附上了一个可重现的例子，它用我遇到的问题生成了一个图表。感谢任何可以帮助我的人。

library(magrittr)
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
library(forcats)
library(ggplot2)
library(ggridges)
library(RCurl)
#> Carico il pacchetto richiesto: bitops

y_ex <- c("y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1","y1")
x_ex <- c("x1","x1","x2","x3","x3","x3","x3","x3","x3","x4","x4","x4","x5","x5","x5","x5","x5","x5","x5","x5","x5","x5","x5")
value_ex <- c(0.26,0.40,0.47,0.72,0.71,0.69,0.74,0.73,0.24,0.39,0.43,0.46,0.21,0.18,0.14,0.10,0.16,-0.10,-0.11,0.56,0.50,0.49,0.43)

data_ex <- data.frame(y_ex,x_ex,value_ex)

r_ex <- data_ex %>% 
  dplyr::mutate(x_ex = forcats::fct_reorder(x_ex, desc(value_ex), fun = mean))

r_ex %>% 
  ggplot(aes(x = value_ex, y = x_ex)) + 
  ggtitle(paste0("Predictors of ",y_ex)) +
  geom_density_ridges(fill = "royalblue",
                      scale = 0.9,
                      color = NA, 
                      alpha = 0.7,
                      rel_min_height = 0.01) +
  geom_point(size = 0.5, alpha = 0.5, pch = 16) +
  geom_point(data = r_ex %>% group_by(x_ex) %>% dplyr::summarise(value_ex = mean(value_ex)),
             color = "firebrick",
             pch = 16,
             alpha = 0.5) +
  scale_y_discrete("") +
  scale_x_continuous("", limits = c(0, 1)) +
  theme_grey(base_size = 16, base_family = "serif") +
  theme(plot.title = element_text(hjust = 0.5,
                                  lineheight = .8, 
                                  face = "bold",
                                  margin = margin(10, 0, 20, 0),
                                  color = "gray15"),
        legend.position = "none") 
#> Picking joint bandwidth of 0.0453
#> Warning: Removed 2 rows containing non-finite values (stat_density_ridges).
#> Warning: Removed 2 rows containing missing values (geom_point).`

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Answer 1

正在发生的情况是，缩放启发式被丢失的数据搞混了。缩放启发式获取基线y值的总范围，并将其除以组的数量- 1，请参见here。

在您的示例中，缩放启发式生成的参考比例恰好是因子2太大，因此您应该使用scale = 0.45来获得与scale = 0.9相同的效果(如果没有任何缺失的级别)。

请注意，所有区域都需要一起缩放，因为分布下的区域需要具有相同的大小(某些单位为1)。您的x5分布不是很高，因为它们是双峰分布，因此范围更广。