ZDD : Overview of ZDD Operators and Methods : permitsym : Select itemsets by number of items

3.42 permitsym : Select itemsets by number of items

Format

$obj$ .permitsym( $zdd1$ ) $\rightarrow$ $zdd2$

Description

Among all itemsets that make up ZDD object $obj$ , select the itemsets containing the items equal to or below the number defined in $zdd1$ , and return as ZDD object $zdd2$ .

Example

Example 1: Basic Example

> require 'zdd'
> a=ZDD::itemset("a")
> b=ZDD::itemset("b")
> c=ZDD::itemset("c")
> d=ZDD::itemset("d")
> x=5*a + 3*b + b*c + 2
> x.show
 5 a + b c + 3 b + 2

# Select itemsets with less than or equal to 1 item 
> x.permitsym(1).show
 5 a + 3 b + 2

# Select itemsets with less than or equal to 2 items
> x.permitsym(2).show
 5 a + b c + 3 b + 2

# Select itemsets without any item (that is empty itemsets) 
> x.permitsym(0).show
 2

See Also