更改条形图中特定条形的颜色

Question

我一直在创建一些条形图,我想知道是否可以在图表上显示颜色条,这取决于它们是位于x轴的上方还是下方？

为了澄清,这是我所说的条形图类型:

理想情况下,我希望能够将单独颜色上方的条形颜色设置为下方,以便图形看起来更具吸引力,我一直在寻找,但我找不到任何方法这样做,任何人都可以帮忙吗？

提前致谢.:)

Answer 1

这是一个策略:

## Create a reproducible example
set.seed(5)
x <- cumsum(rnorm(50))

## Create a vector of colors selected based on whether x is <0 or >0  
## (FALSE + 1 -> 1 -> "blue";    TRUE + 1 -> 2 -> "red")
cols <- c("blue", "red")[(x > 0) + 1]  

## Pass the colors in to barplot()   
barplot(x, col = cols)

如果您需要两种以上的基于值的颜色,则可以采用类似的策略(使用findInterval()代替简单的逻辑测试):

vals <- -4:4
breaks <- c(-Inf, -2, 2, Inf)
c("blue", "grey", "red")[findInterval(vals, vec=breaks)]
# [1] "blue" "blue" "grey" "grey" "grey" "grey" "red"  "red"  "red" 

Answer 2

甲ggplot2使用溶液geom_bar用stat_identity.

library(ggplot2)
ggplot(dat, aes(x= seq_along(x), y = x)) + 
  geom_bar(stat = 'identity', aes(fill = x>0), position = 'dodge', col = 'transparent') + 
  theme_bw() + scale_fill_discrete(guide = 'none') + 
  labs(x = '', y = 'NAO Index')

scale_fill_discrete(guide = 'none')删除图例,position = 'dodge'停止来自默认值的警告position = 'stack'.

Answer 3

一种方法是使用逻辑或因子变量索引颜色向量(这是R中常见的习语).

set.seed(1)
NAO <- rnorm(40)
cols <- c("red","black")
pos <- NAO >= 0
barplot(NAO, col = cols[pos + 1], border = cols[pos + 1])

这里的诀窍是pos:

> pos
 [1] FALSE  TRUE FALSE  TRUE  TRUE FALSE  TRUE  TRUE  TRUE FALSE
[11]  TRUE  TRUE FALSE FALSE  TRUE FALSE FALSE  TRUE  TRUE  TRUE
[21]  TRUE  TRUE  TRUE FALSE  TRUE FALSE FALSE FALSE FALSE  TRUE
[31]  TRUE FALSE  TRUE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE

我们在barplot()通话中强制使用数字 :

> pos + 1
 [1] 1 2 1 2 2 1 2 2 2 1 2 2 1 1 2 1 1 2 2 2 2 2 2 1 2 1 1 1 1 2
[31] 2 1 2 1 1 1 1 1 2 2

的矢量1S和2S选用从颜色的向量元素cols,使得:

> cols[pos + 1]
 [1] "red"   "black" "red"   "black" "black" "red"   "black"
 [8] "black" "black" "red"   "black" "black" "red"   "red"  
[15] "black" "red"   "red"   "black" "black" "black" "black"
[22] "black" "black" "red"   "black" "red"   "red"   "red"  
[29] "red"   "black" "black" "red"   "black" "red"   "red"  
[36] "red"   "red"   "red"   "black" "black"

这是传递给每个绘制条形的颜色.

在上面的代码中,我还通过参数将条形的边框设置为相关颜色border.

结果图应该如下所示