为geom_bar图创建垂直颜色渐变 [英] Creating a vertical color gradient for a geom_bar plot

问题描述

我进行了搜索，但是似乎找不到一种优雅的方式！

I have searched and searched, but I cant seem to find an elegant way of doing this!

我有一个数据集Data，由Data$x(日期)和Data$y(数字从0到1)组成

I have a dataset Data consisting of Data$x (dates) and Data$y (numbers from 0 to 1)

我想将它们绘制在条形图中:

I want to plot them in a bar-chart:

ggplot(Data) + geom_bar(aes(x = x, y = y, fill = y, stat = "identity")) +
   scale_fill_gradient2(low = "red", high = "green", mid = "yellow", midpoint = 0.90)

结果看起来像这样

但是，我想给每个条在垂直方向上设置一个从0(红色)到y(取决于y的绿色)范围的渐变.有什么办法可以顺利地做到这一点?

However, I wanted to give each bar a gradient in the vertical direction ranging from 0 (red) to y (greener depending on y). Is there any way of doing this smoothly?

我试图查看是否可以将图片强加给黑客，但是我不能将其强加给酒吧，除非是超级丑陋的方式.

I have tried to see if I could impose a picture on the graph as a hack, but I can't impose it on the bars only except in a super super ugly way.

推荐答案

另一种(不是很漂亮)使用geom_segment进行黑客入侵. x的开始和结束位置(x和xend)被硬编码(- 0.4; + 0.4)，size也是如此.这些数字需要根据x值的数量和y的范围进行调整.

Another, not very pretty, hack using geom_segment. The x start and end positions (x and xend) are hardcoded (- 0.4; + 0.4), so is the size. These numbers needs to be adjusted depending on the number of x values and range of y.

# some toy data
d <- data.frame(x = 1:3, y = 1:3)

# interpolate values from zero to y and create corresponding number of x values
vals <- lapply(d$y, function(y) seq(0, y, by = 0.01))
y <- unlist(vals)
mid <- rep(d$x, lengths(vals))
d2 <- data.frame(x = mid - 0.4,
                 xend = mid + 0.4,
                 y = y,
                 yend = y)

ggplot(data = d2, aes(x = x, xend = xend, y = y, yend = yend, color = y)) +
  geom_segment(size = 2) +
  scale_color_gradient2(low = "red", mid = "yellow", high = "green", 
                        midpoint = max(d2$y)/2) 

一个有点相关的问题，可能会给您一些其他想法:

A somewhat related question which may give you some other ideas: How to make gradient color filled timeseries plot in R

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