Manual annotate a ggplot with different labels, in different facets

Question

JD Long helped me with this: question about manual annotation.

But is it possible to do something similar on a facetted plot, such that the label style corresponds to the linestyle (aestetics) and in a way that I can annotate different facets individually?

Some data:

funny <- structure(list(Institution = structure(c(1L, 1L, 1L, 1L, 2L, 
2L, 2L, 2L, 3L, 3L, 3L, 3L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 3L, 
3L, 3L, 3L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 1L, 
1L, 1L, 1L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L), .Label = c("Q-branch", 
"Some-Ville", "Spectre"), class = "factor"), Type = structure(c(5L, 
6L, 1L, 3L, 5L, 6L, 2L, 4L, 5L, 6L, 2L, 4L, 5L, 6L, 2L, 4L, 5L, 
6L, 2L, 4L, 5L, 6L, 2L, 4L, 5L, 6L, 2L, 4L, 5L, 6L, 2L, 4L, 5L, 
6L, 2L, 4L, 5L, 6L, 2L, 4L, 5L, 6L, 2L, 4L, 5L, 6L, 2L, 4L), .Label = c("Korte videregående uddannelser", 
"Mammas beer", "Mellemlange videregående uddannelser", "Tastes good", 
"Unknown", "Your"), class = "factor"), År = c(2008L, 2008L, 
2008L, 2008L, 2008L, 2008L, 2008L, 2008L, 2008L, 2008L, 2008L, 
2008L, 2007L, 2007L, 2007L, 2007L, 2007L, 2007L, 2007L, 2007L, 
2007L, 2007L, 2007L, 2007L, 2007L, 2007L, 2007L, 2007L, 2007L, 
2007L, 2007L, 2007L, 2007L, 2007L, 2007L, 2007L, 2006L, 2006L, 
2006L, 2006L, 2006L, 2006L, 2006L, 2006L, 2006L, 2006L, 2006L, 
2006L), Mndr = c(3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 15L, 15L, 
15L, 15L, 15L, 15L, 15L, 15L, 15L, 15L, 15L, 15L, 27L, 27L, 27L, 
27L, 27L, 27L, 27L, 27L, 27L, 27L, 27L, 27L), Data = c(159L, 
NA, NA, 23L, 204L, NA, NA, 12L, 256L, NA, NA, 24L, 166L, 6L, 
NA, 43L, 228L, NA, NA, 20L, 196L, 11L, NA, 37L, 99L, 14L, 9L, 
96L, 147L, 7L, 5L, 91L, 100L, 10L, 7L, 126L, 60L, 17L, 6L, 106L, 
78L, 18L, 13L, 140L, 48L, 23L, 5L, 136L)), .Names = c("Institution", 
"Type", "År", "Mndr", "Data"), class = "data.frame", row.names = c(NA, 
-48L))

And a facetted plot:

ggplot(funny, aes(Mndr, y=Data, group=Type, col=Type)) +
  geom_line() +
  facet_grid(.~Institution)

Thanks in advance for your help!

Answer 1

The idea is that for each manual annotation you have to define not only the label, but all the variables that define the panel, color, etc. The following code adds two labels in different panels.

pl <- ggplot(funny, aes(Mndr, y=Data, group=Type, col=Type))+geom_line()
      +facet_grid(.~Institution)   #your plot
nd <- data.frame(Institution=c("Q-branch","Some-Ville"),  #panel
                 Type=c("Unknown", "Tastes good"),        #color
                 Mndr=c(7,12),                            #x-coordinate of label
                 Data= c(170,50),                         #y-coordinate of label
                 Text=c("Label 1", "Label 2"))            #label text
# add labels to plot:
pl <- pl + geom_text(aes(label=Text), data=nd, hjust=0, legend=FALSE)
pl

The legend=FALSE option will ensure that the small a's denoting the text are not added to the legend. You don't have to have a data frame for the labels, you could have a separate geom_text for each, but I find this way simpler.