Plotting all subgroups - venn diagram

Question

I've been dealing with R recently and I've come across an interesting problem. I have to plot all possible venn diagrams of 9 one-column datasets (let's name them df1...df9). I'm using library(gplots), and the piece of code for venn with an example input is:

venn(list(df1,df2,df3,df4))

The question is: how can I generate all possible subsets of those nine datasets (there are total of 126 - computed used combs function.), and export them in a list, which could be the inputted into venn. So for example: (df1,df2), (df5,df4), (df3,df5,df8) . . . Here I would iterate through all options and plot the venn diagram for each. Thank you for any hints.

Answer 1

Let's start with a reproducible example:

# Sample data (9 15-element subsets of the letters stored in a list)
set.seed(144)
(dfs <- replicate(9, sample(letters, 15), simplify=FALSE))
# [[1]]
#  [1] "b" "r" "y" "l" "g" "n" "a" "u" "z" "s" "j" "c" "h" "x" "m"
# 
# [[2]]
#  [1] "b" "n" "m" "t" "i" "f" "a" "l" "k" "u" "o" "c" "g" "v" "p"
# ...

The venn function doesn't support venn diagrams with more than 5 sets, and venn diagrams with one set are pretty uninteresting. Therefore, I'll limit to subsets with two to five sets:

# Get all subsets with 2-5 elements
subs <- do.call(expand.grid, replicate(length(dfs), c(F, T), simplify=F))
subs <- subs[rowSums(subs) %in% 2:5,]
venns <- apply(subs, 1, function(x) venn(dfs[x], show.plot=F))

venns now contains all 372 of your venn diagram objects. You could plot a particular one with, for instance, plot(venns[[100]])

If you really wanted to plot all the venn diagrams, you might do something like:

apply(subs, 1, function(x) {
  png(paste0("venn_", paste(which(x), collapse="_"), ".png"))
  venn(dfs[x])
  dev.off()
})

This would create 372 image files containing the venn diagrams, named based on the sets that are included.