顏色ggplot線的基礎上增加或減少

Question

我想改變線段的顏色是否大於它之前的點。我在這裏做錯了什麼？

例子：

from [1,4] to [2,5] would be green because the y value is increasing. 
from [1,4] to [2,1] would be red because the y value is decreasing. 

我的代碼：

set.seed(42) 
df<-NULL 
df$x<-rnorm(10,0,10) 
df$y<-rnorm(10,0,10) 
df$colors<-cbind(lapply(1:length(df$x),function(i){ 
    ifelse(df$x[i]>df$x[i-1],"#CC6666","#9999CC") 
})) 
df<-data.frame(df) 


ggplot()+ 
    geom_line(aes(x=df$x,y=df$y),size=1.5,colour=df$color)+ 
    scale_color_manual(values=df$color) 

Answer 1

將這樣的事情對你的工作，我重新安排你的榜樣數據一點，但我們可以用geom_segment()和dplyr::lead()得到顏色匹配正確，並有一點ggplot破解，使標籤再次漂亮，並溝：NA：

set.seed(42) 
df <- data.frame(x = rnorm(10,0,10), 
        y = rnorm(10,0,10)) 

# base R 
df <- df[order(df$x),] 
df$color <- sapply(1:nrow(df), function(i) df$y[i] > df$y[i+1]) 
df$group <- "1" 

library(tidyverse) 
df <- arrange(df, x) %>% 
    mutate(color = y > lead(y), 
      group = "1") # group everything togther or else we get two lines 

ggplot()+ 
    geom_path(data = df, 
       aes(x=x, y=y, color = color, group = group),size=1.5) + 
    scale_color_manual(values = c("#CC6666","#9999CC"), na.value = "white", 
         labels = c("increase", "decrease", ""))