I'm struggling a great deal to modify the legend in my plot. Here is a reproducible example:
dtt <- structure(list(model = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L), .Label = c("ma", "mb", "mc"), class = "factor"), year = c(2005L, 2006L, 2007L, 2008L, 2009L, 2010L, 2005L, 2006L, 2007L, 2008L, 2009L, 2010L, 2005L, 2006L, 2007L, 2008L, 2009L, 2010L), V = c(0.16, 0.14, 0.11, 0.13, 0.15, 0.16, 0.24, 0.17, 0.12, 0.13, 0.15, 0.15, 0.2, 0.16, 0.11, 0.12, 0.12, 0.15), lower = c(0.11, 0.11, 0.07, 0.09, 0.11, 0.12, 0.16, 0.12, 0.04, 0.09, 0.09, 0.11, 0.14, 0.1, 0.07, 0.08, 0.05, 0.1), upper = c(0.21, 0.19, 0.17, 0.17, 0.19, 0.2, 0.29, 0.23, 0.16, 0.17, 0.16, 0.2, 0.26, 0.27, 0.15, 0.16, 0.15, 0.19)), .Names = c("model", "year", "V", "lower", "upper"), class = "data.frame", row.names = c(NA, -18L))
My plot is generated like this:
ggplot(dtt, aes(x=year, y=V, group = model, colour = model, ymin = lower, ymax = upper)) +
geom_ribbon(alpha = 0.35, linetype=0)+
geom_line(aes(linetype=model), size = 1.5) +
geom_point(aes(shape=model), fill = "white", size = 4) +
theme(legend.position=c(.6,0.8)) +
theme(legend.background = element_rect(colour = 'black', fill = 'grey90', size = 1, linetype='solid'))
which produces this:
Now, what I would like to do is
- change the title of the legend
- change the order in which the legend items appear
- change the text of the legend items.
I have fiddled around for hours trying to do this, but without much success. The best I have managed so far is to add this:
scale_colour_hue(name = "Model 1",
breaks=c("mb", "ma", "mc"),
labels=c("MBB", "MAA", "MCC"))
But it produces this abomination:
As you see, there is now an extra unneeded legend, and the shapes in the legend do not match those in the plot !
Finally, I would like to graphics in the legend to indicate that the blue and green lines are dashed, not solid - but I have no idea at all how to do that.
Any assistance would be highly appreciated,
The answer is
You need to do two things:
- Rename and re-order the factor levels before the plot
- Rename the title of each legend to the same title
The code:
dtt$model <- factor(dtt$model, levels=c("mb", "ma", "mc"), labels=c("MBB", "MAA", "MCC"))
library(ggplot2)
ggplot(dtt, aes(x=year, y=V, group = model, colour = model, ymin = lower, ymax = upper)) +
geom_ribbon(alpha = 0.35, linetype=0)+
geom_line(aes(linetype=model), size = 1) +
geom_point(aes(shape=model), size=4) +
theme(legend.position=c(.6,0.8)) +
theme(legend.background = element_rect(colour = 'black', fill = 'grey90', size = 1, linetype='solid')) +
scale_linetype_discrete("Model 1") +
scale_shape_discrete("Model 1") +
scale_colour_discrete("Model 1")
However, I think this is really ugly as well as difficult to interpret. It's far better to use facets:
ggplot(dtt, aes(x=year, y=V, group = model, colour = model, ymin = lower, ymax = upper)) +
geom_ribbon(alpha=0.2, colour=NA)+
geom_line() +
geom_point() +
facet_wrap(~model)
Source: Stackoverflow.com