It's the same question than this one : How do I arrange a variable list of plots using grid.arrange?, but with extra arguments, for example a legend.
Here is a toy example.
Here is the data:
Country = c("France", "Italy", "Peru", "Canada", "Brazill", "Spain", "Macedonia", "Austria")
Diet = c("carnivore", "homnivore", "vegtarian", "vegan")
n = 1000
data1 = data.frame("Country" = sample(Country, n, replace = TRUE),
"Diet" = sample(Diet, n, replace = TRUE),
"X" = sample(c(1 : 20), n, replace = TRUE),
"Y" = sample(rnorm(n)))
Here is an intermediate plot to make a legend:
plot = ggplot(data1, aes(x = Diet, fill = Diet)) + geom_histogram(stat = "count") + theme(legend.position = "bottom")
plot
legend <- cowplot::get_legend(plot)
Here is a list of plot I will arrange with grid.arrange:
Countries = data1$Country %>% unique
n = length(Countries)
l = lapply(c(1 : n), function(x) ggplot(data1 %>% filter(Country == Countries[[x]]), aes(x = Diet, fill = Diet)) + geom_histogram(stat = "count"))
Here is the result I want:
grid.arrange(legend, l[[2]], l[[3]], ncol = 2, layout_matrix = rbind(c(2, 3), c(1, 1)))
Here is how I would like to write it (without writing l[[1]], l[[2]]; useful if I have many plots):
do.call("grid.arrange", c(legend, l[1 : 2], ncol = 2, layout_matrix = rbind(c(2, 3), c(1, 1))))
But it doesn't work.
However it works without the extra arguments:
do.call("grid.arrange", c(l[1 : 2], ncol = 2))
Your issue is how you combine lists. You are doing this:
a <- list(1, 2)
b <- list(list(3, 4), list(5, 6))
c <- 7
c(a, b, c)
As a result, everything gets added to the a list.
What you want is this:
c(list(a), b, c)