getZones | R Documentation |

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

getZones(area, snames, ellipse = FALSE)

`area` |
A chgaracter expression written in sum of products form. |

`snames` |
A string containing the sets' names, separated by commas. |

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

A SOP ("sum of products") is also known as a DNF ("disjunctive normal form"), or in other
words a "union of intersections", for example ** A*D + B*c**.

The same expression can be written in curly brackets notation:
** A{1}*D{1} + B{1}*C{0}**.

The expression ** B{1}*C{0}** can also be written in a pseudo-language, as
"-10-" (assuming there are only four sets).

A "zone" is a union of set intersections. There are exactly ** 2^k** intersections
in a Venn diagram, where

`k`

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

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

venn(3) area <- getZones("A", snames = "A, B, C") # a list of length 1 polygon(area[[1]], col="lightblue") # The very same result is obtained with: zone <- getZones("1--") # for 5 sets, the content of the 5th set but not in the first set is a # list of two zones venn(5) zones <- getZones("0---1") # 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")

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