I have a panel like the following. I want to add some info in the unused space, but don't know how to incorporate a custom legend or annotation into that space which I've indicated with blue:
Here's my code
p %>%
ggplot( aes(x=year, y=prop1)) +
geom_line( group=1, aes(color=group), color="black", size=1.2 )+
geom_line(data=p %>% dplyr::select(-group), aes(group=group2), color="grey", size=0.5, alpha=0.5) +
theme_bw() +
ggtitle("a panel") +
facet_wrap(~name)+
theme(
strip.background = element_blank(),
strip.text.x = element_blank()
)