基于ggplot的可視化系統：cowplot

GitHub 主頁：

https://github.com/wilkelab/cowplot

CRAN 包地址：

http://cran.r-project.org/web/packages/cowplot/index.html

包描述：

The cowplot package is a simple add-on to ggplot2. It is meant to provide a publication-ready theme for ggplot2, one that requires a minimum amount of fiddling with sizes of axis labels, plot backgrounds, etc. Its primary purpose is to give my students and postdocs an easy way to make figures that I will approve of. Thus, this package meets my personal needs and tastes. Yours may be different.

Some helpful extensions and modifications to the ‘ggplot2′ library. In particular, this package makes it easy to combine multiple ‘ggplot2′ plots into one and label them with letters, e.g. A, B, C, etc., as is often required for scientific publications. The package also provides a streamlined and clean theme that is used in the Wilke lab, hence the package name, which stands for Claus O. Wilke’s plot library.

包解讀：

現在每次繪制GGplot的圖，都會使用 theme_bw（）去除灰色的背景信息，現在使用cowplot 似乎變的很簡單，圖的排列和注釋也變得很簡單。

代碼實例：

代碼：

library(ggplot2)
    require(cowplot)
    plot.mpg <- ggplot(mpg, aes(x = cty, y = hwy, colour = factor(cyl))) +
                geom_point(size=2.5)

    plot.diamonds <- ggplot(diamonds, aes(clarity, fill = cut)) +
                     geom_bar() +
                     theme(axis.text.x = element_text(angle=70, vjust=0.5))

    plot.iris <- ggplot(iris, aes(Sepal.Length, Sepal.Width)) +
                 geom_point() + facet_grid(. ~ Species) +
                 stat_smooth(method = "lm") +
                 background_grid(major = 'y', minor = "none") +
                 panel_border()

    ggdraw() +
      draw_plot(plot.iris, 0, .5, 1, .5) +
      draw_plot(plot.mpg, 0, 0, .5, .5) +
      draw_plot(plot.diamonds, .5, 0, .5, .5) +
      draw_plot_label(c("A", "B", "C"), c(0, 0, 0.5), c(1, 0.5, 0.5), size = 15)

結果：