Question

I wish to recreate this graph:

(from here)

Using R base graphics.

I have no clue how to do that. Any advice ?

(My motivation is that I wish to create a plot where the line width (and/or color) will reflect another dimension. Until now – ggplot2 is the only place I found in R for how to do this. I would be happy to be able to do this also in base R)

Answer 1

OK, I spent a little too much time messing with this… note the last line is the ggplot version so you can compare the two.

#loess and error curves almost just like ggplot2
op <- par(las=1, mar = c(3,3,1,1))
n <- 30
x <- sort(rnorm(n)) #(varying density in predictor)
x <- x + abs(min(x))
x <- x/max(x)*2*pi 
y <- sin(x)+rnorm(n) #(curvy)
m <- loess(y~x)
xx <- seq(min(x), max(x), (max(x)-min(x))/1000) #increase density of values to predict over to increase quality of curve
f <- predict(m, xx, se = TRUE)
ci <- f$se * qt(0.975, f$df)
cih <- f$fit + ci
cil <- f$fit - ci
plot(x,y, ylim = c(min(cil,y), max(cih,y)), cex.axis = 0.85, xlab = '', ylab = '', type = 'n')
title(xlab = 'x', ylab = 'y',line = 2)
grid(col = 'gray')
points(x,y, pch = 19, cex = 0.65)
lines(xx, f$fit, col = 'blue', lwd = 1.2)
xx <- c(xx, rev(xx))
yy <- c(cil, rev(cih))
polygon(xx, yy, col=rgb(0.1,0.1,0.1,0.25), border = NA)
par(op)

#qplot(x,y, geom = 'point') + stat_smooth()