如何使用ggplot2将条线覆盖在条形图上？ [英] How can a line be overlaid on a bar plot using ggplot2?

问题描述

我正在寻找一种方法来绘制包含两个不同系列的条形图，隐藏其中一个系列的条形图，而是有一条线（如果可能的话，可以平滑）通过隐藏系列的条形顶部已经（类似于在直方图上覆盖频率多项式的方式）。我试过了下面的例子，但似乎遇到了两个问题。

首先，我需要按组总结（总计）数据，其次， （df2）转换为一行。

  df < -  data.frame（grp = c （AABBCC）val = c（1,1,2,2,3,3） -  data.frame（grp = c（A，A，B，B，C，C），val = c（1,4,3,5,1,2） ）
 ggplot（df，aes（x = grp，y = val））+ 
 geom_bar（stat =identity，alpha = 0.75）+ 
 geom_bar（data = df2，aes x = grp，y = val），stat =identity，position =dodge）
  

解决方案

也许您的示例数据并不代表您正在使用的真实数据，但是没有要绘制的 df2 。每个x和y值只有一个值。这里有一个修改版本的 df2 ，它有足够的数据点来构建行：

  df < -  data.frame（grp = c（A，A，B，B，C，C），val = c（1,2,3,1 ，2,3））
 df2 < -  data.frame（grp = c（A，A，B，B，C，C），val = c （1,4,3,5,0,2））
 
p < -  ggplot（df，aes（x = grp，y = val））
p < -  p + geom_bar （stat =identity，alpha = 0.75）
 
p + geom_line（data = df2，aes（x = grp，y = val），color =blue）
  geom_point（data = df2，aes（x = grp，y = val），color =red，size = 6）。你可以明显地改变颜色和大小，你喜欢。
 
 
 
编辑：在回应评论
 
 
 
我不完全确定直方图上的频率多项式的视觉效果应该是什么样子。 x值是否应该相互连接？其次，你继续提到想要的行，但你的代码显示 geom_bar（），我认为这不是你想要的吗？如果您需要线条，请使用 geom_lines（）。如果上面的两个假设是正确的，那么这里有一个方法来做到这一点： 
 
 
  #First让我们按组$ b $总结df2 （df2，...（grp），总结，total = sum（val））
> df3 
 grp total 
 1 A 5 
 2 B 8 
 3 C 3 
 
＃第二，让我们在处理grp变量时将df3绘制为一条线作为数字
 
p <-ggplot（df，aes（x = grp，y = val））
p <-p + geom_bar（alpha = 0.75，stat =identity）
p + geom_line（data = df3，aes（x = as.numeric（grp），y = total），color =red）
  
 
I'm looking for a way to plot a bar chart containing two different series, hide the bars for one of the series and instead have a line (smooth if possible) go through the top of where bars for the hidden series would have been (similar to how one might overlay a freq polynomial on a histogram).  I've tried the example below but appear to be running into two problems.


First, I need to summarize (total) the data by group, and second, I'd like to convert one of the series (df2) to a line.
df <- data.frame(grp=c("A","A","B","B","C","C"),val=c(1,1,2,2,3,3))  
df2 <- data.frame(grp=c("A","A","B","B","C","C"),val=c(1,4,3,5,1,2))  
ggplot(df, aes(x=grp, y=val)) +   
    geom_bar(stat="identity", alpha=0.75) +  
    geom_bar(data=df2, aes(x=grp, y=val), stat="identity", position="dodge")

解决方案
Perhaps your sample data aren't representative of the real data you are working with, but there are no lines to be drawn for df2. There is only one value for each x and y value. Here's a modifed version of your df2 with enough data points to construct lines:
df <- data.frame(grp=c("A","A","B","B","C","C"),val=c(1,2,3,1,2,3))
df2 <- data.frame(grp=c("A","A","B","B","C","C"),val=c(1,4,3,5,0,2))

p <- ggplot(df, aes(x=grp, y=val)) 
p <- p + geom_bar(stat="identity", alpha=0.75) 

p + geom_line(data=df2, aes(x=grp, y=val), colour="blue")
Alternatively, if your example data above is correct, you can plot this information as a point with geom_point(data = df2, aes(x = grp, y = val), colour = "red", size = 6). You can obviously change the color and size to your liking.

EDIT: In response to comment

I'm not entirely sure what the visual for a freq polynomial over a histogram is supposed to look like. Are the x-values supposed to be connected to one another? Secondly, you keep referring to wanting lines but your code shows geom_bar() which I assume isn't what you want? If you want lines, use geom_lines(). If the two assumptions above are correct, then here's an approach to do that:
 #First let's summarise df2 by group
 df3 <- ddply(df2, .(grp), summarise, total = sum(val))
>  df3
  grp total
1   A     5
2   B     8
3   C     3

#Second, let's plot df3 as a line while treating the grp variable as numeric

p <- ggplot(df, aes(x=grp, y=val))
p <- p + geom_bar(alpha=0.75, stat = "identity") 
p + geom_line(data=df3, aes(x=as.numeric(grp), y=total), colour = "red")


                        
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