如何使用ggplot2获得带有自由刻度和条形图的facet_grid图?

我正在(重新)学习 ggplot2 并尝试获取此特殊代码情节，这被证明是非常回避的.

I'm (re)learning ggplot2 and trying to get this particular plot, which is proving quite evasive.

我早些时候发现了此问题，这很有用，但不是我需要的一切.这或多或少是你得到的使用对该问题的公认答案:

Earlier I found this question, which was useful, but not everything I need. This is more or less what you get using the accepted answer to that Q:

## Packages & data:
require(dplyr)
set.seed(0)
df <- data.frame(categ=c("A", "B", "C"), 
                 V1=rpois(3, 20), 
                 V2=rnorm(3, 100, 40), 
                 V2=runif(3)) %>% gather(Var, X, 2:4)
## Se below in "Example data" for how to get this example

p  <- ggplot(df, aes(categ, X, color=Var)) + geom_point()
p + facet_grid(Var ~ ., scale="free")

结果图是这样的:

但是，我需要这样做，只用条形图而不是点数即可.有人需要帮助吗?

However, I need to do the same, only with barplots instead of just points. Anyone with some help?

预先感谢，胡安

请注意，我使用了 tidyr :: ghather 和 magrittr 的管道％>％来创建我的例如，但是使用 reshape2 :: melt :

Note that I used tidyr::ghather and magrittr's pipe %>% to create my example, but the same can be achieved with reshape2::melt:

require(reshape2)
set.seed(0)
df <- data.frame(categ=c("A", "B", "C"), 
                 V1=rpois(3, 20), 
                 V2=rnorm(3, 100, 40), 
                 V2=runif(3))
df <- melt(df, id="categ", variable.name="Var", value.name="X")

无论如何，生成的 data.frame 看起来像这样:

Anyway, the resultant data.frame looks like this:

categ  Var           X
    A   V1  25.0000000
    B   V1  18.0000000
    C   V1  25.0000000
    A   V2 150.8971729
    B   V2 116.5856574
    C   V2  38.4019983
    A V2.1   0.1765568
    B V2.1   0.6870228
    C V2.1   0.3841037