I have a "spaghetti plot" showing individual courses of HbA1c for two different groups of subjects, together with a separate smooth for each group of subjects. I would like to have the luminosity for the individual subjects much lighter and the smooths darker so that the two smooths are easier to see. I have tried several things but I haven't been able to work out the magic. I tried setting 'scale_colour_hue(l=80)' for the individual lines, but that didn't seem to do anything. My code is below, and my current figure, with the individual lines and the two smooths with the same intensity. I suppose that I could also specify new colors for the smooths, but again, I haven't succeeded.
Any help will be deeply appreciated.
ggplot(hba1c[hba1c$StudyID >5,], aes(NumDaysInitial/365.25,HbA1c,group=PatientID, color=as.factor(StudyID))) + geom_line() + scale_colour_hue(l=80) + geom_smooth(aes(group = as.factor(StudyID)), se = F) + theme(legend.position = "bottom") + scale_color_discrete(name ="CIT Study") + scale_x_continuous(breaks=seq(-4,8,2)) + labs(x = "Years relative to first PHPI transplant", title = "Course of HbA1c, CIT-07 & CIT-06 subjects")