如何使用 ggplot2 在 facet_wrap 中分组 top_n 后对条形图进行排序？

Question

在分组变量后使用facet_wrap （通常在此处、 此处和其他地方报告）并获取最高值时，我遇到了排序条的问题。 当我在没有因子转换的情况下运行代码时，条形图是有序的：

iris %>% 
  gather(key = measurements, value = values, - Species) %>% 
  mutate(kk = factor(measurements, levels = unique(.$measurements)),
         species_l = with(., paste(Species, .$measurements, sep = "_"))) %>% 
  ggplot(aes(x = reorder(species_l, values),
             y = values, 
             fill = kk)) +
  geom_bar(stat = "identity") +
  facet_wrap(.~kk,
             scales = "free")

但是现在我想在facet_wrap和top_n之后订购递减的酒吧。 到目前为止，这是我尝试过的：

library(tidyverse)
iris %>% 
  gather(key = measurements, value = values, - Species) %>% 
  within(., 
         Species <- factor(Species, 
                          levels=names(sort(table(Species), 
                                            decreasing=FALSE)))) %>% 
  ggplot(aes(x = Species,
             y = values, 
             fill = measurements)) +
  geom_bar(stat = "identity") +
  facet_wrap(.~ measurements,
             scales = "free") 

和这个：

iris %>% 
  gather(key = measurements, value = values, - Species) %>% 
  group_by(measurements, Species) %>% 
  top_n(5, wt = values) %>% 
  ggplot(aes(x = reorder(Species, Species,
                         function(x)-length(x)),
             y = values, 
             fill = measurements)) +
  geom_bar(stat = "identity") +
  facet_wrap(.~measurements,
             scales = "free")

和这个：

iris %>% 
  gather(key = measurements, value = values, - Species) %>% 
  mutate(kk = factor(measurements, levels = unique(.$measurements)),
         species_l = with(., paste(Species, .$measurements, sep = "_"))) %>% 
  group_by(measurements, Species) %>%
  top_n(5, wt = values) %>%
  ungroup() %>%
  ggplot(aes(x = reorder(species_l, values),
             y = values, 
             fill = kk)) +
  geom_bar(stat = "identity") +
  facet_wrap(.~kk,
             scales = "free")

这就是我得到的：

如您所见Sepal.Width条未排序。

Answer 1

您的第一次尝试很接近 - 您需要确保您正在重新排序每个方面，而不仅仅是根据所有测量的前 5 个值重新排序因子。 Julia Silge在这里彻底解释

library(tidytext) 
library(tidyverse)
library(magtrittr)

iris %>%
   gather(key = measurements, value = values, - Species) %>% 
    mutate(kk = factor(measurements, levels = unique(.$measurements)),
#The '-values' below specifies to order in descending
      Species = reorder_within(Species, -values, measurements)) %>% 
   ggplot(aes(x = Species, y = values, fill = kk)) +
      geom_bar(stat = "identity") +
        facet_wrap(.~kk, scales = "free") +
      scale_x_reordered()`