venn (version 1.2)

getZones: Calculate the union(s) of set intersections.

Description

This function uses a metacommand to calculate the shape of a specific zone or a list of zones.

Usage

getZones(ints, nofsets, ellipse = FALSE)

Arguments

ints

A vector of decimal numbers specific to a list of set intersection.

nofsets

The number of sets.

ellipse

Logical, get the zones from the shape of an ellipse, where possible

Value

A list of self-enclosed polygons, for each independent zone.

Details

A "zone" is a union of set intersections. There are exactly 2^k intersections in a Venn diagram, where k is the number of sets. To highlight an entire set, we need a union of all possible intersections which form that set.

In a 3 sets diagram, the (overall) first set is composed by four intersections: 100 for what is in the first set but outside sets 2 and outside set 3 101 for the intersection between sets 1 and 3, outside set 2 110 for the intersection between sets 1 and 2, outside set 3 111 for the intersection between all three sets.

The decimal representation for these intersections is calculated as: 100 = 2^2 = 4 101 = 2^2 + 2^0 = 5 110 = 2^2 + 2^1 = 6 111 = 2^2 + 2^1 + 2^0 = 7

The argument ellipse retrieves the data from the shape of an ellipse, and it only works with 4 and 5 sets.

Examples

# NOT RUN {
venn("1--")

zone <- getZones(4:7, 3)
# a list of length 1

polygon(zone[[1]], col="lightblue")


# for 5 sets, the content of the 5th set but not in the first set is a
# list of two zones

venn("0---1")

zones <- getZones(seq(1, 15, by = 2), 5)
# this time a list of length 2

# (re)coloring the first zone (union)
polygon(zones[[1]], col="lightblue")

# and the second zone (union)
polygon(zones[[2]], col="lightblue")

# }