plotrix (version 3.8-2)

makeIntersectList: Count set intersections

Description

Create a list of set intersections from a matrix of indicators

Usage

makeIntersectList(x,xnames=NULL,sep="+")

Value

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

Arguments

x

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). x can also be a matrix or data frame in which the first column contains object identifiers and the second contains attribute codes.

xnames

Optional user-supplied names for the attributes of x.

sep

A character to use as a separator for attribute labels.

Author

Jim Lemon

Details

makeIntersectList reads a matrix (or data frame where all values are the same type) containing dichotomous values (either 0/1 or FALSE/TRUE) or labels (see next paragraph). In the first type of input, 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 x is all zeros, it will not be counted, but the second last element of the list returned contains the count of rows in x and thus non-members can be calculated.

If a matrix (or data frame where all values are the same type) containing values other than 0/1 or TRUE/FALSE, it will be passed to categoryReshape for conversion to a data frame as described above. See categoryReshape for details of this.

makeIntersectList combines the set or attribute names to form intersection names. For the intersection of sets A and B, the name will be A+B (unless sep is changed) and so on. These are the names that will be displayed by intersectDiagram. To change these, use the xnames argument.

See Also

intersectDiagram, pasteCols,categoryReshape

Examples

 # 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)))
 makeIntersectList(setdf)
 ns<-sample(1:8,20,TRUE)
 objects<-0
 for(i in 1:length(ns)) objects<-c(objects,rep(i,ns[i]))
 attributes<-"Z"
 for(i in 1:length(ns)) attributes<-c(attributes,sample(LETTERS[1:8],ns[i]))
 setdf2<-data.frame(objects[-1],attributes[-1])
 makeIntersectList(setdf2)