makeIntersectList: Count set intersections

Description

Create a list of set intersections from a matrix of indicators.

Usage

makeIntersectList(x,xnames=NULL)

Arguments

A data frame or matrix where rows represent objects and columns attributes. A 1 or TRUE indicates that the object (row) has that attribute or is a member of that set (column).

xnames

Optional user-supplied names for the categories of x.

Value

A list of the intersection counts or percentages and the total number of objects.

Details

makeIntersectList reads a matrix (or data frame) containing only dichotomous values (either 0/1 or FALSE/TRUE). Each row represents an object and each column represents a set. A value of 1 or TRUE indicates that that object is a member of that set. The function creates a list of vectors that correspond to all combinations of the sets (set intersections) and inserts the counts of elements in each combination. If a row of the matrix is all zeros, it will not be counted, but the last element of the list returned contains the count of rows in x and thus non-members can be calculated. makeIntersectList combines the set or attribute names to form intersection names. For the intersection of sets A and B, the name will be AB and so on. These are the names that will be displayed by intersectDiagram. To change these, use the xnames argument.

Examples

Run this code

# create a matrix where each row represents an element and
 # a 1 (or TRUE) in each column indicates that the element is a member
 # of that set.
 setdf<-data.frame(A=sample(c(0,1),100,TRUE,prob=c(0.7,0.3)),
  B=sample(c(0,1),100,TRUE,prob=c(0.7,0.3)),
  C=sample(c(0,1),100,TRUE,prob=c(0.7,0.3)),
  D=sample(c(0,1),100,TRUE,prob=c(0.7,0.3)))
 setdflist<-makeIntersectList(setdf)
 setdflist