使用ggplot多行并居中对齐X轴标签

Question

我知道hjust用于x title轴，但是如何使x轴标签居中且支持多行？这是我的绘图函数：

gg_fun<-function(){
  ggplot(tab,                  
         aes(x = Var1, y = Percent)) +
    #theme_light() +
    theme(panel.background = element_rect(fill = NA),
          axis.title.y=element_text(angle=0, vjust=0.5, face="bold"), 
          axis.title.x=element_blank(),
          axis.text.y = element_text(size = 10), 
          axis.text.x = element_text(size = 12),
          axis.ticks.x = element_blank(),
          axis.ticks.y = element_blank(),
          #panel.grid.minor = element_line(colour = "dark gray"),
          panel.grid.major.x = element_blank() ,
          # explicitly set the horizontal lines (or they will disappear too)
          panel.grid.major.y = element_line(size=.1, color="dark gray" ),
          axis.line = element_line(size=.1, colour = "black"),
          plot.background = element_rect(colour = "black",size = 1)) +
    geom_bar(stat = "Identity", fill="#5596E6") + #"cornflower" blue
    ggtitle(element_blank()) + 
    scale_y_continuous(expand =  c(0, 0), breaks = round(seq(0, 1, by = .1), digits = 2), 
                       labels  = percent(round(seq(0, 1, by = .1), digits = 2), digits = 0),
                       limits = c(0,.6)) #+
    #scale_x_discrete()
}

这里是一个示例图表：

我知道scale_x_discrete()的n.dodge参数，但这不是我想要的。我也不想仅仅使用labels = abbreviate或者精确指定，因为这很费时间。例如，我还看到过这样的方法：levels(birds$effect) <- gsub(" ", "\n", levels(birds$effect))，但这种方法跳过了每一行，并使一些标签变得太长。如何让x轴文本居中并多行显示以防止重叠？以下是我想要的示例：

- hkj447

Answer 1

你可以使用 stringr::str_wrap 作为 scale_x_discrete 的标签函数。

让我们来看一些示例数据：

tab <- data.frame(Var1 = c("Video of presentation incl visuals",
                          "Video of presentation, written text and visuals",
                          "Written text, plus visuals",
                          "Other (please specify)"),
                 Percent = c(0.33, 0.34, 0.16, 0.17))

使用您的原始函数，将生成以下图表：

gg_fun()

但是进行以下修改：

gg_fun<-function(){
  ggplot(tab,                  
         aes(x = Var1, y = Percent)) +
    #theme_light() +
    theme(panel.background = element_rect(fill = NA),
          axis.title.y=element_text(angle=0, vjust=0.5, face="bold"), 
          axis.title.x=element_blank(),
          axis.text.y = element_text(size = 10), 
          axis.text.x = element_text(size = 12),
          axis.ticks.x = element_blank(),
          axis.ticks.y = element_blank(),
          #panel.grid.minor = element_line(colour = "dark gray"),
          panel.grid.major.x = element_blank() ,
          # explicitly set the horizontal lines (or they will disappear too)
          panel.grid.major.y = element_line(size=.1, color="dark gray" ),
          axis.line = element_line(size=.1, colour = "black"),
          plot.background = element_rect(colour = "black",size = 1)) +
    geom_bar(stat = "Identity", fill="#5596E6") + #"cornflower" blue
    ggtitle(element_blank()) + 
    scale_y_continuous(expand =  c(0, 0), 
                       breaks = round(seq(0, 1, by = .1), digits = 2), 
                       labels  = scales::percent(round(seq(0, 1, by = .1), 
                                                       digits = 2), digits = 0),
                       limits = c(0,.6)) +
    scale_x_discrete(labels = function(x) stringr::str_wrap(x, width = 16))
}

我们得到：

gg_fun()

- Allan Cameron

Answer 2

通常情况下，您需要手动在标签中放置换行符'\n'。但是，有人编写了一个自动执行此操作的函数，并在this thread中提供了该函数。

- Thomas Lemon