如何在R中的facet_grid中调整y轴

Question

我使用facet_grid制作了构面图。看起来就像我想要的一样，除了y轴看起来卡在图中外，数据以百分比表示，并且它的取值范围是（3％-95％）。有没有办法使它看起来更好？

plot <- ggplot(data=mydata, mapping=aes(x=year, y=value)) +
  geom_bar(stat="identity", aes(color=coralType))

我尝试使用：

plot + facet_grid(coralType ~ location, scales="free")

和

plot + facet_grid(coralType ~ location, scales="free_x") 
plot + facet_grid(coralType ~ location, scales="free_y")

我也尝试过ylim=c(3, 100) ylim=range(3:100)

没有一个起作用。

这是我的数据：

structure(list(location = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = c("site01", "site02", 
"site03", "site04", "site05", "site06", "site07", "site08"), class = "factor"), 
    coralType = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 
    2L, 2L, 2L, 2L, 2L, 2L), .Label = c("blue corals", "hard corals", 
    "sea fans", "sea pens", "soft corals"), class = "factor"), 
    longitude = c(143.515, 143.515, 143.515, 143.515, 143.515, 
    143.515, 143.515, 143.515, 143.515, 143.515, 143.515, 143.515, 
    143.515, 143.515, 143.515), latitude = c(-11.843, -11.843, 
    -11.843, -11.843, -11.843, -11.843, -11.843, -11.843, -11.843, 
    -11.843, -11.843, -11.843, -11.843, -11.843, -11.843), year = c(2010L, 
    2011L, 2012L, 2013L, 2014L, 2015L, 2016L, 2017L, 2011L, 2012L, 
    2013L, 2014L, 2015L, 2016L, 2017L), value = c(30, 30, 41, 
    43, 50, 54, 57, 58, 10, 11, 30, 31, 31, 32, 34)), row.names = c(NA, 
15L), class = "data.frame")

Answer 1

根据OP提供的数据，由

生成的图

ggplot(mydata) + 
  aes(x = year, y = value, fill = coralType) +
  geom_col() + 
  facet_grid(coralType ~ location)

看起来不错，因为value是数字。

请注意，使用fill美学代替了colour美学。此外，geom_col()用作geom_bar(stat = "identity")的快捷方式。

---

当将value绘制为字符时，我可以重现该问题（ggplot2变成了一个因数）：

max_value <- 60
ggplot(mydata) + 
  aes(x = year, y = sprintf("%.2f %%", 100 * value / max_value),
      fill = coralType) +
  geom_col() + 
  facet_grid(coralType ~ location)

由于数据点数量有限，这看起来不像OP的屏幕截图那样混乱。

---

如果OP希望在y轴上显示百分比而不是绝对值，则可以将scale_y_continuous(labels = scales::percent)与数值一起使用：

max_value <- 60
ggplot(mydata) + 
  aes(x = year, y = value / max_value, fill = coralType) +
  geom_col() + 
  facet_grid(coralType ~ location) + 
  scale_y_continuous(labels = scales::percent)

数据

mydata <-
structure(list(location = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = c("site01", "site02", 
"site03", "site04", "site05", "site06", "site07", "site08"), class = "factor"), 
    coralType = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 
    2L, 2L, 2L, 2L, 2L, 2L), .Label = c("blue corals", "hard corals", 
    "sea fans", "sea pens", "soft corals"), class = "factor"), 
    longitude = c(143.515, 143.515, 143.515, 143.515, 143.515, 
    143.515, 143.515, 143.515, 143.515, 143.515, 143.515, 143.515, 
    143.515, 143.515, 143.515), latitude = c(-11.843, -11.843, 
    -11.843, -11.843, -11.843, -11.843, -11.843, -11.843, -11.843, 
    -11.843, -11.843, -11.843, -11.843, -11.843, -11.843), year = c(2010L, 
    2011L, 2012L, 2013L, 2014L, 2015L, 2016L, 2017L, 2011L, 2012L, 
    2013L, 2014L, 2015L, 2016L, 2017L), value = c(30, 30, 41, 
    43, 50, 54, 57, 58, 10, 11, 30, 31, 31, 32, 34)), row.names = c(NA, 
15L), class = "data.frame")