布局类似于facet_grid的facet_wrap

Question

使用facet_grid根据提供的变量中的因子级别包装面板，即使没有给定组合的数据也是如此。这就是我追求的行为。

遗憾的是，y轴比例不能独立于单个面板级别(请参阅here和here)。为此，您必须使用facet_wrap。

但是，facet_wrap不提供与facet_grid相同的布局，并且只显示具有要绘制的值的面板。

如何保持facet_grid-like布局，但具有独立的y轴比例？如果没有数据的面板是空白/无效的，只要它们占据适当的空间就可以了。

可重现的例子：

library(ggplot2)
set.seed(1)

# Generate data
test <- data.frame(x = c(rep(1, 6), rep(2, 6)), 
                   facet_1 = rep(c("A", "A", "A", "B", "B", "C"), 2),
                   facet_2 = rep(c("B", "C", "D", "C", "D", "D"), 2),
                   y = c(1e0, 1e1, 1e2, 1e3, 1e4, 1e5, rnorm(1, 1e0, 1e0*.34), rnorm(1, 1e1, 1e1*.34), rnorm(1, 1e2, 1e2*.34), rnorm(1, 1e3, 1e3*.34), rnorm(1, 1e4, 1e4*.34), rnorm(1, 1e5, 1e5*.34)))

# facet_grid - Shows blank panels B-B, B-C, and C-C. This is what I want.
#            - Does NOT scale y appropriately at the individual panel level.
ggplot(test, aes(x = x, y = y)) +
  facet_grid(facet_2 ~ facet_1, scales = "free") +
  geom_line()

​

​

# facet_wrap - Does NOT show blank panels B-B, B-C, and C-C.
#            - Does scale y appropriately at the individual panel level.
ggplot(test, aes(x = x, y = y)) +
  facet_wrap(vars(facet_1, facet_2), scales = "free") +
  geom_line()

​

​

Answer 1

您可以complete丢失的组合，然后绘制。

library(ggplot2)

tidyr::complete(test, facet_1, facet_2, fill = list(x = 0, y = 0)) %>%
#Keeping them as NA would give a blank plot
#tidyr::complete(test, facet_1, facet_2) %>%
   ggplot() + aes(x = x, y = y) +
   facet_wrap(vars(facet_1, facet_2), scales = "free") +
   geom_line()

​

​

这会给你一个警告，因为在这3组中只有一个观察值。