在构面之间更改配色方案

问题描述

我有一个data.frame，如下所示:

set.seed(100)

df <- data.frame(year = rep(2011:2014, 3),
                 class = rep(c("high", "middle", "low"), each = 4),
                 age_group = rep(1:3, each = 4),
                 value = sample(1:2, 12, rep = TRUE))

并且我希望通过facet -ing(通过变量age_group)产生三个与以下代码产生的图相似的图:

and I am looking to produce, by facet-ing (by the variable age_group) three plots which look similar to those produced by the following code:

library(ggplot2)
blue <- c("#bdc9e1", "#74a9cf", "#0570b0")
ggplot(df) + geom_bar(aes(x = year, y = value,
                          fill = factor(class, levels = c("high", "middle", "low"))),
                      stat = "identity") +
  scale_fill_manual(values = c(blue)) +
  guides(fill = FALSE)

但是，每个方面都有不同的配色方案，其中所有颜色都是由我自己指定的.

however, where each facet has a different colour scheme where all the colours are specified by myself.

我似乎想要这里发生的事情的更具体版本:

I appear to want a more specific version of what is going on here: ggplot2: Change color for each facet in bar chart

因此，根据我提供的数据，我希望获得三个多面图，并按age_group进行划分，其中每个图中的填充度均按class的级别指定，并且所有颜色(共9种) )由我自己手动指定.

So, using the data I have provided, I am looking to get three facet-ed plots, split by age_group where the fill is given in each plot by the level of class, and all colours (9 total) would be specified manually by myself.

为澄清起见，以下代码的确提供了我想最后介绍的方面:

For clarification, the facet that I would like to end up with is indeed provided by the following code:

ggplot(df) + geom_bar(aes(x = year, y = value,
                          fill = factor(class, levels = c("high", "middle", "low"))),
                      stat = "identity") +
  scale_fill_manual(values = c(blue)) +
  guides(fill = FALSE) +
  facet_wrap(~ age_group)

通过class变量增加了对颜色子集的控制级别.

with the added level of control of colour subset by the class variable.

推荐答案

我不确定为什么要这么做，所以很难知道我是否要这么做.提出了您的实际用例的地址.

I'm not entirely sure why you want to do this, so it is a little hard to know whether or not what I came up with addresses your actual use case.

首先，我生成了一个不同的数据集，该数据集实际上在每个age_group中都有每个类:

First, I generated a different data set that actually has each class in each age_group:

set.seed(100)

df <- data.frame(year = rep(2011:2014, 3),
                 class = rep(c("high", "middle", "low"), each = 12),
                 age_group = rep(1:3, each = 4),
                 value = sample(1:2, 36, rep = TRUE))

如果要在每个age_group中寻找类似的明暗梯度，则可以直接使用alpha完成此操作，而不必担心添加额外的数据列:

If you are looking for a similar dark-to-light gradient within each age_group you can accomplish this directly using alpha and not worry about adding extra data columns:

ggplot(df) +
  geom_bar(aes(x = year, y = value,
               fill = factor(age_group)
               , alpha = class ),
           stat = "identity") +
  facet_wrap(~age_group) +
  scale_alpha_discrete(range = c(0.4,1)) +
  scale_fill_brewer(palette = "Set1"
                    , name = "age_group")

在这里，我将alpha的范围设置为可以给出合理可见的颜色，并且只是从RColorBrewer中选择了一个默认调色板来显示该想法.这给出了:

Here, I set the range of the alpha to give reasonably visible colors, and just chose a default palette from RColorBrewer to show the idea. This gives:

它也提供了一个相对可用的图例作为起点，尽管您可以进一步对其进行修改(这是我对另一个问题的类似图例回答:)

It also gives a relatively usable legend as a starting point, though you could modify it further (here is a similar legend answer I gave to a different question: https://stackoverflow.com/a/39046977/2966222 )

或者，如果您真的要自己指定颜色，则可以在数据中添加一列，然后根据该颜色作为基础颜色:

Alternatively, if you really, really want to specify the colors yourself, you can add a column to the data, and base the color off of that:

df$forColor <-
  factor(paste0(df$class, " (", df$age_group , ")")
         , levels = paste0(rep(c("high", "middle", "low"), times = 3)
                           , " ("
                           , rep(1:3, each = 3)
                           , ")") )

然后，将其用作填充.请注意，这里我使用RColorBrewer brewer.pal来选择颜色.我发现第一种颜色太浅，无法显示出类似这样的条形，因此我将其排除在外.

Then, use that as your fill. Note here that I am using the RColorBrewer brewer.pal to pick colors. I find that the first color is too light to show up for bars like this, so I excluded it.

ggplot(df) +
  geom_bar(aes(x = year, y = value,
               fill = forColor),
           stat = "identity") +
  scale_fill_manual(values = c(brewer.pal(4, "Blues")[-1]
                               , brewer.pal(4, "Reds")[-1]
                               , brewer.pal(4, "Purples")[-1]
                               )
                    , name = "Class (age_group)") +
  facet_wrap(~age_group)

给予:

图例非常繁忙，但可以修改为类似于我链接到的其他答案.这样一来，您就可以设置所需的9种颜色(或更多，用于不同的用例).

The legend is rather busy, but could be modified similar to the other answer I linked to. This would then allow you to set whatever 9 (or more, for different use cases) colors you wanted.

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