is.superset: Find Super and Subsets

Description

Provides the generic functions and the S4 methods is.subset and is.superset for finding super or subsets in associations and itemMatrix objects.

Usage

is.subset(x, y = NULL, proper = FALSE, sparse = FALSE, ...)
is.superset(x, y = NULL, proper = FALSE, sparse = FALSE, ...)

Arguments

x, y

associations or itemMatrix objects. If y = NULL, the super or subset structure within set x is calculated.

proper

a logical indicating if all or just proper super or subsets.

sparse

a logical indicating if a sparse (ngCMatrix) rather than a dense logical matrix sgould be returned. This preserves a significant amount of memory for large sets of x and y.

...

currently unused.

Value

returns a logical matrix or a sparse ngCMatrix (for parse=TRUE) with length(x) rows and length(y) columns. Each logical row vector represents which elements in y are supersets (subsets) of the corresponding element in x. If either x or y have length zero, NULL is returned instead of a matrix.

Details

looks for each element in x which elements in y are supersets or subsets. Note that the method can be very slow and memory intensive if x and/or y contain many elements.

Examples

Run this code

data("Adult")
set <- eclat(Adult, parameter = list(supp = 0.8))

### find the supersets of each itemset in set
is.superset(set, set)
is.superset(set, set, sparse = TRUE)