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Question

如何向geom_line（）添加比例颜色以指示线段向上/向下 - 无需使用重塑，dcast预处理数据并创建另一个变量？

library(data.table)
library(ggplot2)

my.data <- data.table(id = c(1,1,2,2,3,3,4,4), 
                  loc = c("a","b","a","b","a","b","a","b"),
                  value = c(10.3,11.5,12.5,12.1,10.5,9.8,9.7,10.7))

p<-ggplot(my.data ,aes(x=loc,y=value,group=id)) + geom_line()

Answer 1

我会做

ggplot(my.data, aes(x=loc,y=value,group=id)) + 
  geom_line(aes(color=ave(value,id,FUN=diff)>=0))