Using nVennR2 to generate and explore n-dimensional, quasi-proportional Venn diagrams

In nVennR2: An Interface to 'nVenn2'

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.show='hide'
)
library(knitr)
uuid <- function() {
  hex_digits <- c(as.character(0:9), letters[1:6])
  hex_digits <- toupper(hex_digits)
  paste(sample(hex_digits, 8), collapse='')
}

subsuid <- function(regex, strng){
  l <- gregexpr(regex, strng, perl = T)
  for (x in regmatches(strng, l)){ 
    m <- regexpr('([^\\{ \\.\\#]+)', x, perl = T)
    names <- regmatches(x, m)
    gstr = strng
    for (name in names){
      nname <- paste('([^\\d\\w<>]', name, ')', sep="")
      gstr <- gsub(nname, paste('\\1', '_', uuid(), sep=""), gstr, perl = T) 
    }
    return(gstr)
  }
}

knit_print.nVennR2 = function(x, ...) {
    g <- getVennSvg(x)
    knitr::asis_output(g)
}
# register the method
registerS3method("knit_print", "nVennObj", knit_print.nVennR2)
local({
  hook_source <- knitr::knit_hooks$get('source')
  knitr::knit_hooks$set(source = function(x, options) {
    x <- x[!grepl('#noshow$', x)]
    hook_source(x, options)
  })
})

Introduction

Proportional Venn diagrams show the relationships between several sets in a compact representation. Each set is depicted as a contiguous area proportional to the number of elements it contains, delimited by a closed curve. Those curves may intersect, creating regions that belong to one or more sets. To be accurate, the area of each region should be proportional to the number of elements it contains.

Representing proportional Venn diagrams with more than two sets is not trivial, as the number of potential regions grows exponentially with the number of sets. The nVenn algorithm represents regions as circles with the desired areas and then encloses those circles in curves to create the sets. The resulting diagrams are approximately proportional and can represent an arbitrary number of sets.

Input

To make a Venn diagram, nVennR2 provides the nVennDiagram function. Its input is either a list of lists, a text with the shape of a table or a previously generated nVenn object.

List of lists

This is the same form of input that the first version of nVennR2 used. Each inner list has a name which is interpreted as the name of the set. The inner list itself contains the elements in that set. The algorithm accepts an arbitrary number of sets, although there is a hard limit in the code of 20 sets. Diagrams of that size would take a very long time to build, and probably would be of little use.

library(nVennR2)
exampledf

myv <- nVennDiagram(exampledf)
myv #noshow

Each time the algorithm is used, the starting conditions are chosen pseudorandomly. This means that executing nVennDiagram again on the same data will result in a different plot.

myv <- nVennDiagram(exampledf, verbose = F)
myv #noshow

This feature is very useful for more complex diagrams. It means that we can run the diagram multiple times and choose which one best represents the data. It also means that it is important to store the result of a good diagram, as there is no guarantee that it may be reproduced. In the examples, myv can be stored with saveRDS and recovered with readRDS.

Text

The native input for nVenn2 is a text table. Sets can be defined in rows or columns. If sets are in rows, the first column must contain set names. If sets are in columns, the first row must contain the set names. In most cases, nVennDiagram can guess if sets are in rows or columns. Users can also make sure that this is correct by providing the byCol parameter (1 means by column, 2 means by row).

toVenn <- 'Set1 Set2 Set3
a a b
b q d
c  e'
myv2 <- nVennDiagram(toVenn, byCol = 1, verbose = F)
myv2 #noshow

Object

The function nVennDiagram also accepts an nVenn object from a previous execution. In that case, it will generate a new Venn diagram with the same data. As in previous cases, the resulting diagram will be different than the previous one.

myv2 <- nVennDiagram(myv2, verbose = F)
myv2 #noshow

Exhaustive mode

In exceptional cases, a user may want to explore the minimization steps in a systematic way. This can be done by setting the maxlevel parameter of nVennDiagram to some value higher than zero. While this procedure may guarantee an optimal diagram if maxlevel is close to the number of regions, it is impractical as the number of regions grows, as the number of combinations to try grows exponentially. Users who want to explore this mode are advised to first get an estimation of the time of computation needed:

estTime <- estimateExhaustiveRunTime(exampledf, 4)
estTime
if (estTime < 10){
  myvEx <- nVennDiagram(exampledf, maxlevel = 4)
  myvEx #noshow
}

Listing elements

Once the diagram is ready, the object returned can be queried to retrieve the elements in each region. A region will usually be represented with a vector of names of the sets it belongs to. In the example with exampledf, stored in myv, the sets are named SAS, PYTHON and R. To find out which elements belong to SAS and R, but not to PYTHON, the region will be c('SAS', 'R').

getVennRegion(myv, c('SAS', 'R'))

We can also list all the elements by region.

regs <- listVennRegions(myv)
regs

Appearance

There are several functions that modify the graphical parameters of the Venn diagram. To see the result of the modifications, we must call plotVenn afterwards. Most parameters can be accessed through setVennOpts except for set colors, which can be edited with setVennPalette and setVennColor or setVennColors. Finally, we can set a list of options and apply them all at once with setVennSkin.

Set graphical options

With setVennOpts, we can tweak the opacity of the fill of sets (opacity), the size of the labels in the sets (fontSize), the width of the line surrounding the sets (lineWidth), the color palette (palette) and whether to show a description of each region (showRegions) or the number of elements in each region (showWeights).

myv2 <- setVennOpts(myv2, opacity = 0.2, lineWidth = 2, palette = 3, showRegions = F)
myv2 #noshow

Set colors

The most straightforward way to change a set color is by using setVennColor. WARNING: colors must be formatted as valid svg color expressions. If we pass an invalid svg color, there may be unexpected results.

myv2 <- setVennColor(myv2, "Set2", 'black')
myv2 #noshow

There are also functions to change several colors at once. First, nVenn has four pre-packaged color palettes (0-3). The key to understand the behavior of nVennR2 is that it first applies a palette and then individual colors. This means that set colors take precedence over palettes. Therefore, if we now apply a different palette, Set2 will still be black.

myv2 <- setVennOpts(myv2, palette = 2)
myv2 #noshow

To apply a palette and override set colors, we can use setVennPalette. This also deletes any set color previously applied with setVennColor or setVennColors.

myv2 <- setVennPalette(myv2, palette = 2)
myv2 #noshow

The other way to change several colors at once is setVennColors. If a vector with svg colors is passed, they will be applied to each set in the same order. If there are more sets than colors, the remaining sets keep their previous color.

colorVector <- c("red", "grey")
myv2 <- setVennColors(myv2, colorVector)
myv2 #noshow

This function also accepts a list, whose names must indicate set names.

colorList <- list(Set1="blue", Set3="#00ff11")
myv2 <- setVennColors(myv2, colorList)
myv2 #noshow

Set skin

Plots generated by nVenn have a defult graphical theme. In addition to changing each parameter, we can define a custom theme and apply it at once. To do this, we simply generate a list with all the parameters we may want to set (those in setVennOpts plus colors) and use setVennSkin. The logical way to use colors in this case is to pass a vector, so that we can apply the theme to any diagram, regardless of the names of the sets.

mytheme <- list(opacity=0.2, lineWidth=2, fontSize=16, showRegions=F, colors=c("red", "green", "blue", "black", "#ffff00"))
myv2 <- setVennSkin(myv2, mytheme)
myv <- setVennSkin(myv, mytheme)
myv2 #noshow
myv #noshow

Rotate the diagram

We can also rotate the plot with rotateVenn. The angle is interpreted in degrees and it is applied counterclockwise.

plotVenn(myv2)
myv2 #noshow
myv2 <- rotateVenn(myv2, 30)
myv2 #noshow

nVennR2 documentation built on July 16, 2026, 9:07 a.m.