如何在facet_grid中指定列或如何更改facet_wrap中的标签 [英] How to specify columns in facet_grid OR how to change labels in facet_wrap

问题描述

我有大量的数据序列，我想使用小倍数进行绘图。 ggplot2和 facet_wrap 的组合可以达到我想要的效果，通常会产生一个很好的6 x 6小方块。这是一个更简单的版本：

I have a large number of data series that I want to plot using small multiples. A combination of ggplot2 and facet_wrap does what I want, typically resulting a nice little block of 6 x 6 facets. Here's a simpler version:

问题是我没有足够的控制标签条中的标签。数据框中列的名称很短，我想以这种方式保留它们，但我希望方面中的标签更具描述性。我可以使用 facet_grid ，这样我就可以利用 labeller 函数，但是似乎没有直接的方法指定列的数量和一长串facet不适用于此特定任务。我是否缺少明显的东西？

The problem is that I don't have adequate control over the labels in facet strips. The names of the columns in the data frame are short and I want to keep them that way, but I want the labels in the facets to be more descriptive. I can use facet_grid so that I can take advantage of the labeller function but then there seems to be no straightforward way to specify the number of columns and a long row of facets just doesn't work for this particular task. Am I missing something obvious?

Q。如何在不更改列名的情况下使用facet_wrap更改构面标签？或者，如何在使用facet_grid时指定列数和行数？

下面是一个简化示例的代码。在现实生活中，我正在处理多个组，每个组包含几十个数据序列，每个数据序列都经常变化，所以任何解决方案都必须自动化，而不是依靠手动赋值。

Code for a simplified example follows. In real life I am dealing with multiple groups each containing dozens of data series, each of which changes frequently, so any solution would have to be automated rather than relying on manually assigning values.

require(ggplot2)
require(reshape)

# Random data with short column names
set.seed(123)
myrows <- 30
mydf <- data.frame(date = seq(as.Date('2012-01-01'), by = "day", length.out = myrows),
                   aa = runif(myrows, min=1, max=2),
                   bb = runif(myrows, min=1, max=2),
                   cc = runif(myrows, min=1, max=2),
                   dd = runif(myrows, min=1, max=2),
                   ee = runif(myrows, min=1, max=2),
                   ff = runif(myrows, min=1, max=2))

# Plot using facet wrap - we want to specify the columns
# and the rows and this works just fine, we have a little block
# of 2 columns and 3 rows

mydf <- melt(mydf, id = c('date'))

p1 <- ggplot(mydf, aes(y = value, x = date, group = variable)) +
    geom_line() +
    facet_wrap( ~ variable, ncol = 2)
print (p1)

# Problem: we want more descriptive labels without changing column names.
# We can change the labels, but doing so requires us to
# switch from facet_wrap to facet_grid
# However, in facet_grid we can't specify the columns and rows...

mf_labeller <- function(var, value){ # lifted bodily from the R Cookbook
    value <- as.character(value)
    if (var=="variable") {
        value[value=="aa"]   <- "A long label"
        value[value=="bb"]   <- "B Partners"
        value[value=="cc"]   <- "CC Inc."
        value[value=="dd"]   <- "DD Company"
        value[value=="ee"]   <- "Eeeeeek!"
        value[value=="ff"]   <- "Final"
    }
    return(value)
}

p2 <- ggplot(mydf, aes(y = value, x = date, group = variable)) +
    geom_line() +
    facet_grid( ~ variable, labeller = mf_labeller)
print (p2)

推荐答案

我不太明白。您已经编写了一个函数，将您的短标签转换为长描述性标签。简单地添加一个新列并在该列上使用 facet_wrap 而不是？

I don't quite understand. You've already written a function that converts your short labels to long, descriptive labels. What is wrong with simply adding a new column and using facet_wrap on that column instead?

mydf <- melt(mydf, id = c('date'))
mydf$variableLab <- mf_labeller('variable',mydf$variable)

p1 <- ggplot(mydf, aes(y = value, x = date, group = variable)) +
    geom_line() +
    facet_wrap( ~ variableLab, ncol = 2)
print (p1)

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