使用ggplot2中的scale_fill_brewer（）函数为数据设置断点 [英] Setting breakpoints for data with scale_fill_brewer() function in ggplot2

问题描述

我正在按照 ggplot2 wiki <>描述的方式创建地图（choropleth） / A>。除了我遇到了通过scale_fill_brewer（）函数将连续值映射到多边形填充颜色的问题之外，所有东西都像魅力一样。

这个问题描述我遇到的问题。就像在答案中一样，我的解决方法是使用gtools quantcut（）函数将我的数据预剪成bin：

更新：这个第一个例子实际上是（$）
$ b

  require（gtools）＃需要的数量（）
 
 ... 
 
 fill_factor<  -  quantcut（fill_continuous，q = seq（0,1，by = 0.25））
 ggplot（mydata）+ 
 aes（long ，lat，group = group，fill = fill_factor）+ 
 geom_polygon（）+ 
 scale_fill_brewer（name =mybins，palette =PuOr）
  

不过，我觉得我应该可以跳过预先裁剪数据的步骤，并使用breaks选项执行此类操作：

  ggplot（mydata）+ 
 aes（long，lat，group = group，fill = fill_continuous）+ 
 geom_polygon（）+ 
 scale_fill_brewer（names =mybins，palette =PuOr，breaks = quantile（fill_continuous））
  

但这不起作用。相反，我得到一个错误：
$ b

提供给离散scale_brewer的连续变量（复合分数）。

我误解了休息选项的用途吗？或者是破裂了？

解决方案

正如Hadley解释的那样，break选项会移动ticks，但不会使数据连续。因此，按照问题中的第一个示例预先裁剪数据是使用scale_fill_brewer命令的正确方法。

I am creating a map (choropleth) as described on the ggplot2 wiki. Everything works like a charm, except that I am running into an issue mapping a continuous value to the polygon fill color via the scale_fill_brewer() function.

This question describes the problem I'm having. As in the answer, my workaround has been to pre-cut my data into bins using the gtools quantcut() function:

UPDATE: This first example is actually the right way to do this

require(gtools) # needed for quantcut()

...

fill_factor <- quantcut(fill_continuous, q=seq(0,1,by=0.25))
ggplot(mydata) + 
aes(long,lat,group=group,fill=fill_factor) +
geom_polygon() +
scale_fill_brewer(name="mybins", palette="PuOr")

This works, however, I feel like I should be able to skip the step of pre-cutting my data and do something like this with the breaks option:

ggplot(mydata) +
aes(long,lat,group=group,fill=fill_continuous) +
geom_polygon() +
scale_fill_brewer(names="mybins", palette="PuOr", breaks=quantile(fill_continuous))

But this doesn't work. Instead I get an error something like:

Continuous variable (composite score) supplied to discrete scale_brewer.

Have I misunderstood the purpose of the "breaks" option? Or is breaks broken?

解决方案

As Hadley explains, the breaks option moves the ticks, but does not make the data continuous. Therefore pre-cutting the data as per the first example in the question is the right way to use the scale_fill_brewer command.

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