ggplot2：显示 x 轴标签的类别和子类别

big_theme <- theme(
  panel.background = element_rect(fill = "black"),
  plot.background = element_rect(fill = "black", colour = NA),
  plot.title = element_text(hjust = 0.5, size = 15, color = "white"),
  axis.text.y = element_text(colour = "white", size = 14),
  axis.title.x = element_text(colour = "white", size = 14),
  axis.title.y = element_text(colour = "white", size = 14),
  axis.text.x = element_text(vjust = 1, angle = 45, color = "white", size = 14, hjust=1),
  strip.background = element_rect(fill = "black"),
  strip.text = element_text(colour = 'white'),
  strip.text.y = element_text(angle = 0), 
  legend.position = "top"
)

theme2 = theme(panel.background = element_rect(fill = 'black'),
  legend.background=element_rect(fill = "black"),
  legend.text = element_text(colour = "white", size = 14), 
  legend.justification = "right",
  legend.key.height = unit(1, "line"),
  legend.key = element_rect(color = "black", fill = "black"))

theme3 = theme(plot.background = element_rect(fill = 'black'))

plot1 <- ggplot(sample_data) + big_theme + theme2 + theme3
plot1 + 
  geom_col(position = "identity", 
           aes(x = category, y = value,
               fill = forcats::fct_relevel(variable, c("z", "x", "y")),
               color = forcats::fct_relevel(variable, c("z", "x", "y")))) + 
  scale_fill_manual(values = c("#000000","#D3667C","#53AC79")) + 
  scale_color_manual(values = c("#00A2EF","#D3667C","#53AC79")) + 
  geom_text(aes(label = big_category, x = big_category, y = 0), vjust = 0, 
            size = 3, color = "white", position = position_dodge(width = 1)) +  
  scale_y_continuous(limits = c(0, 2.4), expand = c(0, 0)) 

我有一个数据集，如下所示：

big_category category   variable    value
a     aa    x   1.2
a     ba    x   1.05
a     ca    x   1.11
a     aa    y   1.43
a     ba    y   1.09
a     ca    y   0.97
a     aa    z   1.12
a     ba    z   1.46
a     ca    z   1.32

b     ab    x   1.2
b     bb    x   1.05
b     cb    x   1.11
b     ab    y   1.43
b     bb    y   1.09
b     cb    y   0.97
b     ab    z   1.12
b     bb    z   1.46
b     cb    z   1.32
c     ac    x   1.2
c     ac    y   1.05
c     ac    z   1.11

我希望 x 轴按类别标记，在其下方我想要 big_category 的标签。例如，我想要 aa、ba 和 ca 的轴标签，然后在 ggplot 中为 big_category a 提供一个标签。我不希望它与类别标签混合在一起，而且我还希望它位于水平显示的 x 轴标签下方。

我也尝试过facet_grid，但这给了我一个问题，因为条形的大小不均匀。就像 big_category a 有 3 个类别，但 big_category c 只有 1 个类别。我希望它们都具有相同的宽度，并且我想要一个连续的图。

Update

big_category category variable value
a aa111111111 x 1.2
a ba111111111 x 1.05
a ca111111111 x 1.11
a aa111111111 y 1.43
a ba111111111 y 1.09
a ca111111111 y 0.97
a aa111111111 z 1.12
a ba111111111 z 1.46
a ca111111111 z 1.32
b ab111111111 x 1.2
b ab111111111 y 1.05
b ab111111111 z 1.11
c ac111111111 x 1.2
c bc111111111 x 1.05
c cc111111111 x 1.11
c ac111111111 y 1.43
c bc111111111 y 1.09
c cc111111111 y 0.97
c ac111111111 z 1.12
c bc111111111 z 1.46
c cc111111111 z 1.32

Code:

big_theme <- theme(
panel.background = element_rect(fill = "black"),
plot.background = element_rect(fill = "black", colour = NA),
plot.title = element_text(hjust = 0.5, size = 15, color = "white"),
axis.text.y = element_text(colour = "white", size = 14),
axis.title.x = element_text(colour = "white", size = 14),
axis.title.y = element_text(colour = "white", size = 14),
axis.text.x = element_text(vjust = 1, angle = 45, color = "white", size = 14, hjust=1),
strip.background = element_rect(fill = "black"),
strip.text = element_text(colour = 'white'),
strip.text.y = element_text(angle = 0),
legend.position = "top"
)

theme2 = theme(panel.background = element_rect(fill = 'black'),
legend.background=element_rect(fill = "black"),
legend.text = element_text(colour = "white", size = 14),
legend.justification = "right",
legend.key.height = unit(1, "line"),
legend.key = element_rect(color = "black", fill = "black"))

theme3 = theme(plot.background = element_rect(fill = 'black'))

ggplot(sample_data %>% mutate(variable=fct_relevel(variable, c("z","x","y")))) +
geom_col(position = "identity",
aes(x = category, y = value, fill = variable, color = variable)) +
facet_grid(. ~ big_category, space="free_x", scales="free_x", switch="x") +
big_theme + theme2 + theme3 +
theme(strip.placement = "outside",
strip.background = element_rect(fill=NA,colour="white"),
panel.spacing.x=unit(0,"cm"),
strip.text = element_text(hjust=0, face="bold", size=12))

下面是一个使用示例数据的示例，说明如何category之内big_category。为了简单起见，我只包含了基本的情节元素。当然，您可以将特定的主题、颜色和其他元素添加到下面的基本图中。

library(tidyverse)

ggplot(sample_data %>% mutate(variable=fct_relevel(variable, c("z","x","y")))) +
  geom_col(position = "identity", 
           aes(x = category, y = value, fill = variable, color = variable)) + 
  facet_grid(. ~ big_category, space="free_x", scales="free_x", switch="x") +
  theme_classic() +
  theme(strip.placement = "outside",
        strip.background = element_rect(fill=NA, colour="grey50"),
        panel.spacing.x=unit(0,"cm"))

UPDATE:如果我理解您的评论，这里有更新的代码，用于左对齐条带文本并删除条带边框。我不知道有什么方法（无需破解 ggplot 之外的底层图形对象）可以在条带之间仅显示垂直线。不过，我在面板之间添加了一些空间，并添加了面板边框来描绘big_category levels.

ggplot(sample_data %>% mutate(variable=fct_relevel(variable, c("z","x","y")))) +
  geom_col(position = "identity", 
           aes(x = category, y = value, fill = variable, color = variable)) + 
  facet_grid(. ~ big_category, space="free_x", scales="free_x", switch="x") +
  theme_bw() +
  theme(strip.placement = "outside",
        strip.background = element_rect(fill=NA,colour=NA),
        panel.spacing.x=unit(0.15,"cm"), 
        strip.text = element_text(hjust=0, face="bold", size=12))

更新2：我创建了一个具有以下更改的绘图：(1)big_categoryx 轴标签左端的标签，以及 (2) 空白big_category标签时category少于 3 个独特关卡。为了保持相同的方面“中断”与空白标签，我们为每个前者创建一个唯一的空白字符串（通过改变字符串的长度）big_category value.

我不认为这个情节看起来很好（实际上我认为它会与big_category侧面条位于其标准位置并且文本居中），但也许您可以尝试一下并获得满足您需求的东西。我已经对代码进行了注释以解释它的作用，但如果有任何不清楚的地方请告诉我。

我们将使用新的sample_data您发布了，但我们将添加第四个级别big_category:

sample_data = sample_data %>% 
  bind_rows(data_frame(big_category="d",
                       category=c("da1111111111", "db111111"),
                       variable=c("z","x"), value=c(1.1,0.6)))

现在我们将进行一些转换sample_data将其设置为绘图并将调整后的数据框直接传输到 ggplot 中：

sample_data %>% 
  mutate(variable=fct_relevel(variable, c("z","x","y"))) %>% 
  # Create grouping column (called short_cat) to mark levels of big_category 
  #  with two or fewer unique levels of category
  group_by(big_category) %>% 
  mutate(short_cat = length(unique(category)) <= 2) %>% 
  ungroup %>% 
  # Create a unique white-space string for each unique value of grp
  mutate(grp = c(0, cumsum(diff(short_cat) != 0)),
         grp = sapply(grp, function(g) paste(rep(" ", g), collapse="")),
         # Assign white-space strings to each level of big_category for which short_cat 
         # is TRUE
         big_category=replace(big_category, short_cat, grp[short_cat]),
         # Set factor order for big_category so new levels will stay in same order 
         #  as original levels
         big_category=factor(big_category, levels=unique(big_category))) %>%
  ggplot() +
    geom_col(position = "identity", width=0.8, 
             aes(x = category, y = value, fill = variable, color = variable)) + 
    facet_grid(. ~ big_category, space="free_x", scales="free_x", switch="x") +
    theme_bw() +
    theme(axis.text.x=element_text(angle=45, vjust=1, hjust=1),
          strip.placement = "outside",
          strip.background = element_rect(fill=NA,colour=NA),
          panel.spacing.x=unit(0.15,"cm"), 
          # Left justify big_category labels
          strip.text = element_text(hjust=0, face="bold", size=12)) +
    # Expand left side of x-axis so that big_category labels will be under left 
    #  end of x-axis labels
    expand_limits(x=-0.5)