【r<-ggplot2】cowplot改变轴位置

作者：Claus O. Wilke

翻译：王诗翔

2018-07-15

从ggplot2的2.2.0版本开始，它本身就支持图形的第二个轴。因此，cowplot的函数switch_axis_position()已经过时了。下面是一些可以用ggplot2实现的例子。

require(cowplot)
require(grid) # for unit()
theme_set(theme_cowplot(font_size=12)) # reduce default font size
p1 <- ggplot(mtcars, aes(mpg, disp)) + geom_line(colour = "blue")

# the following code only works for ggplot2 2.2.0 or later
if (packageVersion("ggplot2")>"2.1.0")
  p1 + theme_gray() + scale_y_continuous(position = "right")

if (packageVersion("ggplot2")>"2.1.0")
  p1 + theme_bw() + scale_x_continuous(sec.axis = dup_axis())

if (packageVersion("ggplot2")>"2.1.0")
  p1 + scale_x_continuous(sec.axis = dup_axis()) + scale_y_continuous(sec.axis = dup_axis())

if (packageVersion("ggplot2")>"2.1.0")
  p1 + theme(axis.ticks.length = unit(0.3, "cm"),
           axis.text.x = element_text(margin = margin(0.2, unit = "cm"))) +
     scale_x_continuous(sec.axis = dup_axis()) + scale_y_continuous(sec.axis = dup_axis())

image.png

这同样适用于离散轴：

mtcars2 <- mtcars[1:15, ]
mtcars2$name <- row.names(mtcars2)

# the following code only works for ggplot2 2.2.0 or later
if (packageVersion("ggplot2")>"2.1.0"){
ggplot(mtcars2, aes(x = name, y = mpg, fill = name)) + 
  geom_bar(stat = 'identity', position = "identity") + 
  scale_y_reverse() +
  guides(fill = FALSE) +
  theme(axis.text.x.top = element_text(angle = 90, vjust=0.5, hjust=0)) +
  scale_x_discrete(position = "top")
}