Draw a line with mixed color in ggplot-CodePudding

I want to draw geom_line with mixed colors used for each line. For example, the lines are drawn in red when the y value is over 0.5 and in blue otherwise. The following is a nasty sketch:

Clearly, we can draw different line segments separately (2 blue segments and 1 red segments). But I still wonder whether we can achieve this in a more convenient way.

Note, I have tried to add a third variable to indicate the color, and supplied that variable to aes(). However, it ended up with something like the figure below,

where the segments of the same color is connected.

CodePudding user response：

Specify a single group so that a single line will be drawn

d = transform(data.frame(x = 1:10, y = c(6:10, 10:6)), col = y > 7)
graphics.off()
ggplot(d, aes(x, y, color = col, group = 1))  
    geom_line(size = 2)