ggplot2中带有学名的多线图字幕

Question

我无法为我的 ggplot2 图表制作字幕。我尝试了答案here，但它仅适用于您有一个学名的情况。就我而言，我想在情节标题中包含两个学名。

这是我想要包含的字幕：

“子弹头金枪鱼 (Auxis rochei) 和海盗鳀鱼 (Encrasicholina punctifer) 的高产量归因于 2016 年上岸量的增加。”

我希望它是多行的，因为它很长。

我的初始代码（一行）：

mysubtitle <- expression(paste("High quantity of Bullet tuna ", italic("Auxis rochei"), " and ", "Buccaneer anchovy ", italic("Encrasicholina punctifer"), " were attributed to the increase in the landings in 2016."))

我试过了：

mysubtitle <- expression(atop(paste("High quantity of Bullet tuna (", italic("Auxis rochei"), ") and ", "Buccaneer anchovy (", italic("Encrasicholina punctifer"), ")"), paste("were attributed to the increase in the landings in 2016.")))

上面的代码生成了一个两行标题，但它是居中的，尽管在我的 ggplot2 主题plot.subtitle = element_text(hjust = 0) 中。我希望它与主情节标题保持一致。

注意：我在主情节标题上没有问题（在 ggplot2 labs 函数中称为title）。仅在subtitle 中。另外，我还有一个单独的主标题。

Answer 1

从“它很愚蠢但它有效”中，您可以在第二行的右侧添加支架字符串以强制左对齐。权利持有者字符串可以是任意字符，长度为nchar(first_line - nchar(second_line))

library(ggplot2)
first_line<- "High quantity of Bullet tuna (Auxis rochei) and Buccaneer anchovy (Encrasicholina punctifer)"
second_line <- "were attributed to the increase in the landings in 2016."
# the length of holder_string
holder_length <- nchar(first_line) - nchar(second_line)
# generate a arbitrary string with length `holder_length`
holder_string <- stringi::stri_rand_strings(1, holder_length)
# the default font family of ggplot is `sans`, we should set the font family as `mono` (monospaced font) to ensure strings between two lines aligned. 
p  <- ggplot(mtcars, aes(wt, mpg))+ geom_point()
p + labs(subtitle = bquote(atop(
  paste("High quantity of Bullet tuna (", 
    italic("Auxis rochei"), ") and ", "Buccaneer anchovy (", 
    italic("Encrasicholina punctifer"), ")"), 
  paste("were attributed to the increase in the landings in 2016.", 
    phantom(.(holder_string))
  )))
) +
theme(plot.subtitle = element_text(family = "mono"))

编辑

或者，你可以使用substitute()

p + labs(subtitle = substitute(atop(
  paste("High quantity of Bullet tuna (", 
    italic("Auxis rochei"), ") and ", "Buccaneer anchovy (", 
    italic("Encrasicholina punctifer"), ")"), 
  paste("were attributed to the increase in the landings in 2016.", 
    phantom(A))
  ),list(A = holder_string))) + 
theme(plot.subtitle = element_text(family = "mono"))

希望对你有帮助！