Change the overlaying order of lines in ggplot

Question

Suppose I have this plot:

library(ggplot2)
pl_data <- data.frame(x = rep(c(1, 2), times = 3), y = c(0, 1, 1, 0, .7, .7), col = rep(c(\"r\", \"b\", \"g\"),         


        

Answer 1

library(ggplot2)
df <- data.frame(
  x = rep(c(1, 2), times = 3), 
  y = c(0, 1, 1, 0, .7, .7), 
  col = rep(c("r", "b", "g"), each = 2))

ggplot() + 
  geom_line(data = df[3:4,], aes(x = x, y = y), color = 'blue', size = 3) +
  geom_line(data = df[5:6,], aes(x = x, y = y), color = 'green', size = 3) +
  geom_line(data = df[1:2,], aes(x = x, y = y), color = 'red', size = 3)

Answer 2

So actually the last level of col is on the top. So you need to change the order of the factor and reverse the colors as red is automatically mapped to the first level (used standard colors to illustrate the problem):

pl_data$col <- factor(pl_data$col, c("r", "g", "b"))
ggplot(pl_data, aes(x = x, y = y, color = col)) +
    geom_line(size = 3) + 
    scale_color_manual(values = c(r = "blue", g = "green", b = "red"))

## with standard colors of ggplot2, function taken from:
## http://stackoverflow.com/questions/8197559/emulate-ggplot2-default-color-palette

ggplotColours <- function(n = 6, h = c(0, 360) + 15) {
  if ((diff(h) %% 360) < 1) h[2] <- h[2] - 360/n
  hcl(h = (seq(h[1], h[2], length = n)), c = 100, l = 65)
}
pal <- setNames(ggplotColours(3), c("b", "g", "r"))
ggplot(pl_data, aes(x = x, y = y, color = col)) +
    geom_line(size = 3) + 
    scale_color_manual(values = pal, breaks = c("b", "g", "r"))