ggplot2, line stacking order for aesthetic mapping of variable

6
votes

I have this situation where I am plotting a series of lines, something like the following:

library(foreach)
library(ggplot2)

df.test <- foreach(ix = seq(0,1,by=0.01),.combine=rbind) %do% {
  theta = seq(-pi,pi,by=pi/100)
  data.frame(IX=ix,theta=theta,value=ix*sin(theta))
}
ggplot(df.test,aes(x=theta,y=value,color=IX,group=IX,order=-IX)) + geom_path() +
  theme_bw() + labs(x="Theta",y="Sin(Theta)",color="Index",title="Example Plot") +
  theme(legend.position=c(0,1),legend.justification=c(0,1))

Which produces a plot as follows:

Sample

If you look closely at the origin, the values of high index value (light blue) are stacked on top of the lines with low index value (dark blue).

How can I reverse this, so that the dark blue lines (low index) are stacked on top of the light blue lines (high index).

The above is analogous to my actual problem, where I am plotting scientific data for various temperatures. The low temperature values are more meaningful than the high temperature values, so I do not want the low temperature lines to be potentially masked by the high temperature lines, in fact the opposite is my preference.

2
rggplot2

2 Answers

2
votes

I think all you need to do is change the colour aesthetic to rev(IX), which will reverse the ordering, and you don't need group or order:

ggplot(df.test, aes(x=theta, y=value, color=rev(IX))) + ...

enter image description here

2
votes

I believe reversing the group order should do it (without changing the colours),

ggplot(df.test,aes(x=theta,y=value,color=IX,group=rev(IX))) + 
    geom_path(lwd=2) +
    theme_bw() + 
    labs(x="Theta",y="Sin(Theta)",color="Index",title="Example Plot") +
    theme(legend.position=c(0,1),legend.justification=c(0,1)) + 
    coord_cartesian(xlim=c(-0.2,0.2), ylim=c(-0.2,0.2))

enter image description here