ggplot2:在自由规模上反转每个方面的离散字符变量的顺序？

Question

我想绘制一个刻面的ggplot2点图.x轴是连续的,y轴是动物列表.根据饮食行为绘制和刻面两个变量.

y轴是自由尺度的,因为每只动物仅出现在一个进食行为类别中.

library(ggplot2)

# First clean up the data set:
msleep.noNA <- msleep[!is.na(msleep$vore),]
msleep.noNA.red <-  msleep.noNA[c(1,3,6,7)]
msleep.noNA.red <- msleep.noNA.red[!is.na(msleep.noNA.red[4]),]
msleep.noNA.red <- melt(msleep.noNA.red)

pg <- ggplot(msleep.noNA.red, aes(value, name, colour = variable)) +
      geom_point() +
      facet_grid(vore ~ ., scale="free_y", space = "free_y")
pg

# Try to reverse order of the y axis:
pg + scale_y_reverse()

# Not possible because its a factor, but it's not classified as such:
class(msleep.noNA.red$name)

有没有人有关于如何在每个子图中按字母顺序排列动物名称的一些线索？

Answer 1

您可以将字符串向量转换为因子并指定级别的顺序:

以下命令将创建一个因子.级别按字母顺序递减:

msleep.noNA.red <- within(msleep.noNA.red,
                         name <- ordered(name, levels = rev(sort(unique(name)))))

现在您可以绘制数据:

pg <- ggplot(msleep.noNA.red, aes(value, name, colour = variable)) +
  geom_point() +
  facet_grid(vore ~ ., scale="free_y", space = "free_y")