如何在ggplot2中获得准确的字体,线条,点和图形大小？

Question

对于最终文章提交,我被要求更新我的数据,以便它们符合以下规范:

1. 轴线为0.25毫米
2. 轴线四周都有刻度线
3. 数据线为0.5毫米
4. 字体是10pt
5. 数字应为80或169毫米宽
6. 必须是300 dpi

我尝试过的:

library(ggplot2)
library(cowplot)
theme_set(theme_bw())

x <- rnorm(100)
mydata <- data.frame(x = x,
                     y = x^2 + runif(100),
                     z = rep(letters[1:4], 25))

p <- ggplot(data = mydata, aes(x, y)) + 
  geom_point(aes(color = z)) + 
  geom_smooth(color = 'black', se = FALSE, size = 0.5) +
  theme(text = element_text(family = 'Times', size = 10, color = 'black'),
        axis.ticks.length = unit(-0.1, 'cm'),
        axis.text.x = element_text(margin = margin(t = 4, unit = 'mm')),
        axis.text.y = element_text(margin = margin(r = 4, unit = 'mm')),
        panel.grid = element_blank(),
        axis.line = element_line(size = 0.25),
        legend.position = c(0.5, 0.75))

p
ggsave(plot = p, 
       filename = 'myplot.png', 
       width = 80, height = 50, dpi = 300, units = 'mm')

p2 <- cowplot::plot_grid(plotlist = list(p, p, p, p), nrow = 1)
ggsave(plot = p2,
       filename = 'mymultipleplot.png',
       width = 169, height = 50, dpi = 300, units = 'mm')

返回以下两个图:

我可以弄清楚如何处理这里的一些问题(例如传说位置),但我遇到以下困难:

1. 如何围绕顶轴和右轴进行刻度？
2. 如何才能使尺寸正确...
   • 这些看起来比10磅大得多.(下载或在新窗口中打开以查看未缩放版本)
   • 尽管在主题(字体,行)中指定,但两个图中的尺寸不会保持不变.
   • 我不知道如何确认线条的大小是正确的(以磅或毫米为单位)......是否ggsave有自己的缩放？

---

更新对于我目前的任务,我导出为svg文件并在Inkscape中进行编辑.花了几个小时,但比让ggplot扭曲到规格更容易.

但是,知道将来如何在ggplot2中以编程方式执行此操作将会很有帮助.

Answer 1

回答问题：1）正如 Henrik 在评论中所说：

对于问题 1（如何获取上轴和右轴周围的刻度？），请参阅 ggplot 2.2.0 中的scale_ 中的新 sec.axis 参数。尝试例如 ggplot(mpg, aes(displ, hwy)) + geom_point() + scale_x_continuous(sec.axis = dup_axis()) + scale_y_continuous(sec.axis = dup_axis())

2）这里的问题是你有相同的分辨率但不同的尺寸。由于两个图形的高度相同，您可以通过手动将字体大小乘以宽度的比例来解决缩放字体大小的问题：例如

theme(text = element_text(family = 'Times', size = 10*(80/169), color = 'black')

整个代码应该如下所示：

library(ggplot2)
library(cowplot)
theme_set(theme_bw())

x <- rnorm(100)
mydata <- data.frame(x = x,
                     y = x^2 + runif(100),
                     z = rep(letters[1:4], 25))

p1 <- ggplot(data = mydata, aes(x, y)) + 
  geom_point(aes(color = z)) + scale_x_continuous(sec.axis = dup_axis()) + 
  scale_y_continuous(sec.axis = dup_axis()) + 
  geom_smooth(color = 'black', se = FALSE, size = 0.5) +
  theme(text = element_text(family = 'Times', size = 10*(80/169), color = 'black'),
        axis.ticks.length = unit(-0.1, 'cm'),
        axis.text.x = element_text(margin = margin(t = 4, unit = 'mm')),


        axis.text.y = element_text(margin = margin(r = 4, unit = 'mm')),

        panel.grid = element_blank(),
        axis.line = element_line(size = 0.25),
        legend.position = c(0.5, 0.75))

p2 <- ggplot(data = mydata, aes(x, y)) + 
  geom_point(aes(color = z)) + scale_x_continuous(sec.axis = dup_axis()) + 
  scale_y_continuous(sec.axis = dup_axis()) + 
  geom_smooth(color = 'black', se = FALSE, size = 0.5) +
  theme(text = element_text(family = 'Times', size = 10, color = 'black'),
        axis.ticks.length = unit(-0.1, 'cm'),
        axis.text.x = element_text(margin = margin(t = 4, unit = 'mm')),


        axis.text.y = element_text(margin = margin(r = 4, unit = 'mm')),

        panel.grid = element_blank(),
        axis.line = element_line(size = 0.25),
        legend.position = c(0.5, 0.75))


p1
ggsave(plot = p1, 
       filename = 'myplot.png', 
       width = 80, height = 50, dpi = 300, units = 'mm')

p2multi <- cowplot::plot_grid(plotlist = list(p2, p2, p2, p2), nrow = 1)

ggsave(plot = p2multi ,
       filename = 'mymultipleplot.png',
       width = 169, height = 50, dpi = 300, units = 'mm')