ggplot2错误：提供给连续标度的离散值 [英] ggplot2 error : Discrete value supplied to continuous scale

问题描述

我有一个名为merged的数据集，它包含3个数字列pauseMedian和numTotalPauses和diff。我也有一个splineHull数据集，它还包含数字列pauseMedian和numTotalPauses，再加上一个6级因子microstyle

我有以下代码，这完美地工作。它绘制一个散点图，然后用splineHull多边形覆盖，这个多边形是根据microstyle着色的。

脚本1：

$ b $

  ggplot（data = merged，aes（x = pauseMedian，y = numTotalPauses））
 + geom_point（）
 + geom_polygon data = splineHull，
 mapping = aes（x = pauseMedian，
y = numTotalPauses，
 group = microstyle，
 color = microstyle），
 alpha = 0）
  

然后，我还想通过添加一个属性color =来改变散点图中点的颜色

脚本2：

  ggplot（data = merged，aes（x = pauseMedian，y = numTotalPauses，color = diff））
 + geom_point（）
 + geom_polygon（data = splineHull，
 mapping = aes（x = PAUS eMedian，
y = numTotalPauses，
 group = microstyle，
 color = microstyle），
 alpha = 0）
  

我看到以下错误：

 错误：提供给连续的离散值规模
  

我不知道为什么我会看到这个错误。如果我仍然想要彩色散点图但没有多边形，我运行下面的代码再次运行。

脚本3：

  ggplot（data = merged，aes（x = pauseMedian，y = numTotalPauses，color = diff））
 + geom_point（）
  

那么，脚本2 发生了什么，错误来自哪里，以及我可以使它工作吗？

解决方案

很明显，对于两种不同的geoms，你不能有不同的颜色美学。作为解决方法，请使用点的填充美学。这意味着您必须使用具有内部填充的点标记样式（请参阅？pch 并向下滚动以获取可用的点样式）。这是一种方法：

  ggplot（）+ 
 geom_point（data = merged，aes（x = pauseMedian ，y = numTotalPauses，fill = diff），
 pch = 21，size = 5，color = NA）+ 
 geom_polygon（data = splineHull，
 mapping = aes（x = pauseMedian，
y = numTotalPauses，
 color = microstyle），
 alpha = 0）
  

<添加 color = NA （在 aes（）之外），去掉点周围的默认黑色边框标记。如果你想在点附近有一个彩色边框，只需将 color = NA 更改为你喜欢的任何颜色即可。

请参阅 ggplot2 Google的此主题讨论类似的问题和一些解决方法。

I have a dataset called "merged", which contains 3 numeric columns "pauseMedian" and "numTotalPauses" and "diff". I also have a splineHull dataset, which also contains numeric columns "pauseMedian" and "numTotalPauses", plus a 6-level factor "microstyle"

I have the following code, which works perfectly. It plots a scatter plop and then overlay it with splineHull polygons colored according to "microstyle".

script 1:

ggplot(data=merged,aes(x = pauseMedian, y = numTotalPauses)) 
       + geom_point()  
       + geom_polygon(data = splineHull, 
                      mapping=aes(x=pauseMedian, 
                                  y=numTotalPauses, 
                                  group=microstyle, 
                                  color = microstyle),
                       alpha=0)

Then, I also want to change the color of the points in the scatter plot by adding just one attribute color = diff.

script 2:

ggplot(data=merged,aes(x = pauseMedian, y = numTotalPauses, color = diff)) 
       + geom_point()  
       + geom_polygon(data = splineHull, 
                      mapping=aes(x=pauseMedian, 
                                  y=numTotalPauses, 
                                  group=microstyle, 
                                  color = microstyle),
                       alpha=0)

I see the following error:

Error: Discrete value supplied to continuous scale

I don't know why I see this error. If I still want colored scatter plot but no polygons, I run the following code it works again.

script 3:

ggplot(data=merged,aes(x = pauseMedian, y = numTotalPauses, color = diff)) 
       + geom_point()  

So, what happened with script 2, where is the error from, and how can I make it work?

解决方案

Evidently, you can't have different color aesthetics for two different geoms. As a workaround, use a fill aesthetic for the points instead. This means you have to use a point marker style that has a filled interior (see ?pch and scroll down for the available point styles). Here's a way to do that:

ggplot() + 
  geom_point(data=merged,aes(x = pauseMedian, y = numTotalPauses, fill = diff),
             pch=21, size=5, colour=NA) +
  geom_polygon(data = splineHull, 
               mapping=aes(x=pauseMedian, 
                           y=numTotalPauses, 
                           colour = microstyle),
               alpha=0) 

Adding colour=NA (outside of aes()), gets rid of the default black border around the point markers. If you want a colored border around the points, just change colour=NA to whatever colour you prefer.

Also see this thread from the ggplot2 Google group, discussing a similar problem and some workarounds.

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