Database Reference
In-Depth Information
Algorithm 9.2 Computation of the positive border (original and revised) Bd
+
(F).
1: procedure PB-C
OMPUTATION
(F)
2:
countf0:::jFjg 0
. initialize counters
3: F
sort
= reverse-sort(F )
4: for each k-itemset f 2 F
sort
do
5: for all (k1)-itemsets q 2 F
sort
do
6: if q f then
7: q:count++
8: end if
9: end for
10: end for
11: for each f 2 F
sort
do
12: if f :count = 0 then
13:
f 2Bd
+
(F)
. add itemset to Bd
+
(F)
14: end if
15: end for
16: end procedure
Algorithm 9.3 Computation of the revised negative border Bd
(F
0
D
) of D.
1: procedure INB-C
OMPUTATION
(F)
2: for k = 1; F
k
6=?; k++ do
3: if k = 1 then
4: for each item x 2 F
1
do
5: if x 2F
0
D
then
. x is infrequent
6: x 2Bd
(F
0
D
)
7: end if
8: end for
9: else if k = 2 then
10: for x 2 F
1
do
11: for y 2 F
1
do
12: if (x < y)^(x ./ y 2 F
2
) then
13: (x ./ y) 2Bd
(F
0
D
)
14: end if
15:
end for
16:
end for
17:
else
. for k > 2
18:
for x 2 F
k1
do
19:
for y 2 F
k1
do
20:
if (x
1
= y
1
)^: : :^(x
k1
< y
k1
) then
21:
z = x ./ y
. z is the join of x and y
22: if z 2F
0
D
;@r
k1
z : r
k1
2 F
0
then
23: z 2Bd
(F
0
D
)
24: end if
25: end if
26: end for
27: end for
28: end if
29: end for
30: end procedure
