An Application of Improved Gap-BIDE Algorithm for Discovering Access Patterns

Algorithm 3

Generate closed sequential patterns.

ALGORITHM: patternGrowth (𝑃)

INPUT: (1) 𝑃: prefix sequence pattern.

OUTPUT: the set of gap-constrained closed sequential

patterns with prefix 𝑃.

(14)backward_check (P needPruning, hasBackwardExtension)

(15)if (needPruning)

(16)return;

(17)forward_check(𝑃, hasForwardExtension);

(18)if ! (hasBackwardExtension ∣∣ hasForwardExtension)

(19)output pattern 𝑃;

(20)search each forward space of all appearances of 𝑃, and

 find the set of all local frequent items, 𝐿;

(21)for each item 𝑖 in 𝐿

(22)build new pattern 𝑃_new = 𝑃 + 𝑖;

(23)call patternGrowth (𝑃_new);

(24)return.