In case you want ggplot2
graphic...
I based this example on that of @EDi. I increased the x
and y
so that the quantile lines would be less wiggly. Because of this increase, I need to use unique(x)
in place of x
in some of the calls.
Here's the modified set-up:
set.seed(1234)
period <- 100
x <- rep(1:100,each=100)
y <- 1*sin(2*pi*x/period) + runif(length(x),-1,1)
require(quantreg)
mod <- rqss(y ~ qss(x))
mod2 <- rqss(y ~ qss(x), tau=0.75)
mod3 <- rqss(y ~ qss(x), tau=0.25)
Here are the two plots:
# @EDi's base graphics example
plot(x, y)
lines(unique(x)[-1], mod$coef[1] + mod$coef[-1], col = 'red')
lines(unique(x)[-1], mod2$coef[1] + mod2$coef[-1], col = 'green')
lines(unique(x)[-1], mod3$coef[1] + mod3$coef[-1], col = 'green')
# @swihart's ggplot2 example:
## get into dataset so that ggplot2 can have some fun:
qrdf <- data.table(x = unique(x)[-1],
median = mod$coef[1] + mod$coef[-1],
qupp = mod2$coef[1] + mod2$coef[-1],
qlow = mod3$coef[1] + mod3$coef[-1]
)
line_size = 2
ggplot() +
geom_point(aes(x=x, y=y),
color="black", alpha=0.5) +
## quantiles:
geom_line(data=qrdf,aes(x=x, y=median),
color="red", alpha=0.7, size=line_size) +
geom_line(data=qrdf,aes(x=x, y=qupp),
color="blue", alpha=0.7, size=line_size, lty=1) +
geom_line(data=qrdf,aes(x=x, y=qlow),
color="blue", alpha=0.7, size=line_size, lty=1)