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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))
zx8754
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armandfavrot
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    Your example uses packages I don't intend to install but I'm pretty sure `c(list(legend), l[1 : 2], list(ncol = 2, layout_matrix = rbind(c(2, 3), c(1, 1))))` would work. – Roland Aug 02 '22 at 08:52
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    The issue probably is that `legend` is a list and `c` adds everything else to that list. – Roland Aug 02 '22 at 08:53
  • The issue is the do.call, "extra arguments" must be passed as a list. – zx8754 Aug 02 '22 at 09:05
  • @Roland I tested your solution, it works, consider submitting as an answer. Or we should try to find a duplicate "how to pass args to do.call". – zx8754 Aug 02 '22 at 09:06
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    @zx8754 The issue is not "how to pass args to `do.call`". The issue is how `c` works with lists. The second `list` I added is probably not even needed. – Roland Aug 02 '22 at 09:08
  • I tried without the second list: `c(list(legend), l[1 : 2], ncol = 2, layout_matrix = rbind(c(2, 3), c(1, 1)))` - It doesn't work. – armandfavrot Aug 02 '22 at 19:07

1 Answers1

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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)
Roland
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