r - ggplot2 多行标题，不同的缩进

Question

我正在为出版物生成图表，我希望能够在 ggplot 本身中标记图形的面板（而不是导出到出版商等），以便它们在最终文档中整齐地组合在一起。我打算通过在标题中添加一个字母（“A”）来尝试做到这一点，但我希望我的标题居中，我希望字母在左上角。

# base graph:

ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species, shape = Species))+
  geom_jitter(size = 6.5)+
  ggtitle("A \n \n The Actual Long, Normal Title of Titliness")+
  theme(plot.title = element_text(hjust = 0.5, face = "bold", size = 30),
        axis.ticks = element_blank(),
        legend.text = element_text(size = 25),
        axis.title = element_text(size = 25, face = "bold"),
        axis.text = element_text(size = 25, vjust = 0.05),
        legend.position = "bottom")

现在，如果我愿意通过手动间隔每个标题来“伪造”它，我可以让它发挥作用，但这似乎既费时又粗糙。

# sloppy solution
ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species, shape = Species))+
  geom_jitter(size = 6.5)+
  ggtitle("A \n \n             The Actual Long, Normal Title of Titliness")+
  theme(plot.title = element_text(hjust = 0,face = "bold", size = 30),
        axis.ticks = element_blank(),
        legend.text = element_text(size = 25),
        axis.title = element_text(size = 25, face = "bold"),
        axis.text = element_text(size = 25, vjust = 0.05),
        legend.position = "bottom")

有没有办法单独调用标题的每一“行”以获得它自己的值？

还有其他创造性的解决方案吗？

此外，我在 mtext 中看到了潜力（使用表达式拆分轴标签），但无法弄清楚如何使用 ggplot2 来实现它（与基本绘图功能相比.. 似乎它们不兼容）。这篇文章很有趣（Multi-line ggplot Title With different Font Size, Face, etc），但我还是 R 新手，我不知道如何编辑这个聪明的东西来改变缩进。

谢谢！

Answer 1

更新：由于 ggplot2 3.0.0 现在有对绘图标签的本机支持，请参阅此答案。

下面是我的做法，使用我专门为此目的编写的 cowplot 包。请注意，您会获得一个干净的主题作为奖励。

library(cowplot)

p <- ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species, shape = Species)) +
  geom_jitter(size = 3.5) +
  ggtitle("The Actual Long, Normal Title of Titliness")

# add one label to one plot
ggdraw(p) + draw_plot_label("A")

# place multiple plots into a grid, with labels
plot_grid(p, p, p, p, labels = "AUTO")

然后，您希望使用该save_plot函数来保存绘图而不是ggsave，因为save_plot具有默认值和参数，可以帮助您获得相对于主题的正确缩放，特别是对于网格中的绘图。

Answer 2

因为ggplot2 3.0.0，有一种本地方法可以做到这一点，使用tag标签：

ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species, shape = Species)) +
  geom_point() +
  labs(title = "The Actual Long, Normal Title of Titliness",
       tag = "A")

Answer 3

最简单的方法可能是使用标题和副标题，

ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species, shape = Species))+
  geom_jitter(size = 6.5) +
  labs(title = "A", subtitle = "The Actual Long, Normal Title of Titliness") +
  theme(plot.subtitle = element_text(hjust = 0.5))

Answer 4

您可以通过操纵 Grobs 来做到这一点。在. gtable_ grid_ggplot2

library("ggplot2")
library("gtable")
library("grid")

p <- ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species, shape = Species))+
  geom_jitter(size = 6.5)+
  ggtitle("The Actual Long, Normal Title of Titliness")+
  theme(plot.title = element_text(hjust = 0.5, face = "bold", size = 30),
        axis.ticks = element_blank(),
        legend.text = element_text(size = 25),
        axis.title = element_text(size = 25, face = "bold"),
        axis.text = element_text(size = 25, vjust = 0.05),
        legend.position = "bottom",
        plot.margin = unit(c(4, 1, 1, 4), "lines"))  # We need bigger top/left margins to show the letter

gt <- ggplot_gtable(ggplot_build(p))  # Building a gtable from the ggplot object
# Adding the textGrob for the panel letter
panel_letter = textGrob("A", x = 0.5, y = .9, 
                        just = c("left", "top"), 
                        gp = gpar(fontsize = 40, col =  "black", face="bold"))
gt <- gtable_add_grob(gt, panel_letter, t=1, l=1, r=1)  # Append the Grob to the table

p <- grid.draw(gt)  # Display the plot
ggsave("plot.png",gt, width=10, height=10)  # If you want to save it.

Answer 5

您可以使用grid.textfrom package grid，将文本添加到您的情节中。首先在您的标题 use 上方添加一些空间plot.margin。

library(grid)
p <- ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species, shape = Species))+
geom_jitter(size = 6.5)+
ggtitle("The Actual Long, Normal Title of Titliness")+
theme(plot.title = element_text(hjust = 0,face = "bold", size = 30),
      axis.ticks = element_blank(),
      legend.text = element_text(size = 25),
      axis.title = element_text(size = 25, face = "bold"),
      axis.text = element_text(size = 25, vjust = 0.05),
      legend.position = "bottom", 
      plot.margin = unit(c(4, 3, 1, 1), "lines"))
p
grid.text('A', x = unit(0.1, 'npc'), y = unit(.90, 'npc'), gp = gpar(fontsize=28))