The output of calculate.overlap is not clear. There are some names for each position of venn diagram such as: $a1 , $a2 , ... It becomes so complicated when we draw it for five
There is an answer here. However, I do not claim to understand it. The general rule to order the regions in a Venn diagram is to use a binary representation of it. My nVennR
package uses that representation and can give you a quick answer for any number of sets:
> library(nVennR)
> myV <- plotVenn(list("A"=c("a","b","c"), "B"=c("a","b","c","d"), "C"=c("a","c","d")), showPlot = F)
> listVennRegions(myV)
$`0, 1, 1 (B, C)`
[1] "d"
$`1, 1, 0 (A, B)`
[1] "b"
$`1, 1, 1 (A, B, C)`
[1] "a" "c"
> listVennRegions(myV, na.rm = F)
$`0, 0, 0 ()`
[1] NA
$`0, 0, 1 (C)`
[1] NA
$`0, 1, 0 (B)`
[1] NA
$`0, 1, 1 (B, C)`
[1] "d"
$`1, 0, 0 (A)`
[1] NA
$`1, 0, 1 (A, C)`
[1] NA
$`1, 1, 0 (A, B)`
[1] "b"
$`1, 1, 1 (A, B, C)`
[1] "a" "c"
There is a vignette with more details on usage.