r - Venn Diagram with Item labels

Question

Suppose I have two vectors

foo <- c('a','b','c','d')
baa <- c('a','e','f','g')

Does anyone know of a way to produce a venn diagram but have the vector items visualised within the diagram.

Like so? (made in powerpoint)

Answer 1

A quick solution using the venn.diagram function from the VennDiagram package. The labels (counts) are hard coded in the function so can't be changed using function arguments. But for a simple example like this you can change the grobs yourself.

library(VennDiagram)

# your data
foo <- c('a','b','c','d')
baa <- c('a','e','f','g')

# Generate plot
v <- venn.diagram(list(foo=foo, baa=baa),
                  fill = c("orange", "blue"),
                  alpha = c(0.5, 0.5), cat.cex = 1.5, cex=1.5,
                  filename=NULL)

# have a look at the default plot
grid.newpage()
grid.draw(v)

# have a look at the names in the plot object v
lapply(v,  names)
# We are interested in the labels
lapply(v, function(i) i$label)

# Over-write labels (5 to 7 chosen by manual check of labels)
# in foo only
v[[5]]$label  <- paste(setdiff(foo, baa), collapse="
")  
# in baa only
v[[6]]$label <- paste(setdiff(baa, foo)  , collapse="
")  
# intesection
v[[7]]$label <- paste(intersect(foo, baa), collapse="
")  

# plot  
grid.newpage()
grid.draw(v)

Which produces

Obviously this method would quickly get out of hand with more categories and intersections.